Under The Eye of the Dragon

by ComsatAngel

10th Dr & Rose: answering an SOS, they end up on a planet orbiting a sun about to explode, amongst a mission plagued by murder, sabotage and paranoia. Not only that they didn't send the SOS. So who did? And why?

UNDER THE EYE OF THE DRAGON

ONE

'Annnd this one,' exhilarated the Doctor, pointing to a tiny green light near the huge time-rotor, which was characteristically wheezing and groaning away, 'Picks up signals that tell me where and when to gatecrash a party!'

Rose glanced at the cylindrical bulb, tugged her tee-shirt sleeves, crossed her arms and merely raised an eyebrow.

The Doctor, seeing she wasn't convinced, shrugged, brushed his fringe out of his eyes and grinned again.

'Well, it might do! You see, the thing is, I didn't design or build the TARDIS. I can operate her, barely – should be half a dozen of us to do the job properly – but I don't know everything there is to know about her.'

Some cheek! thought Rose to herself. In one of his periodical bouts of manic enthusiasm, the Doctor had decided to give her a crash course in how to operate the most basic functions of the time-travelling spaceship. After all, he averred, if it came to the crunch and she had to press a button or pull a lever and didn't know which one it ought to be then there'd be big trouble – and why wait until the crunch? So now here they were in orbit above the earth, a short hop to help get the background right.

She gave an exasperated sigh at the Doctor's mock-despair. Turning and taking in the inside of the supposed "police box", she re-acquainted herself with the sheer, immense, unquantifiable alien-ness of the TARDIS. Complacency sometimes set in unless she stood back, metaphorically, the way she did now thanks to her mentor's insisting on her knowing everything. His infections joie de vivre was one of his most appealing qualities, but when it shaded into joie de mechanique Rose felt considerably less enthused.

'Couldn't you just let me have a look at the User's Manual?' she asked, typically getting to the gist of the matter as the Doctor burbled on.

'This bank here are the Parity and Chronoplasty indicators, showing Galifreyan Zero, Greenwich Mean – sorry? User's Manual?' and the Doctor looked up in surprise from the console, his droopy fringe covering one eye.

'Yeah. An Instruction Manual. Pretty useful things, you know. Mickey always gets stuck into his latest bit of computer kit straight away but I like to read the Manual. That's why his PC's end up exploding and mine don't.'

The Time Lord straightened up and looked suddenly shifty, then worried. His eyes fixed on a point over Rose's shoulder. She suddenly wondered if she hadn't perhaps overstepped the mark, referring to an article that only the now-extinct Gallifreyan culture could have created.

'An instruction manual. "A User's Guide to TARDIS Operation".' His expression softened into a more wry and amused form. 'Splendid idea, Rose! You don't know any car thieves on your estate, do you?'

A year before, or even six months earlier, she might have been thrown by this abrupt change of subject. Not now.

'They aren't my friends, but I know a few. Ecky, and Stevie Edge, and his brother Martin. Oh, and Barky Harky.'

The Doctor nodded, pursing his lips and frowning.

'And do they get instruction manuals for the cars they steal?'

Rose snorted in amused contempt.

'Do they what! No, they get six months each from the magistrate when – er, you did mean "steal"? Steal as in S-T-E-A-L, not S-T-E-E-L?'

Mutely, the Doctor nodded, moving quickly to play around with a series of dials and switches. He looked back at Rose, eyes twinkling.

'You stole the TARDIS!' exclaimed Rose, both amused and horrified. Her companion shrugged, that typical gesture of amicable dismissal. 'There's no manual telling you how to use it because you stole it!'

'Yeah, I did, but that was back in my younger days, back when I looked a lot older. Look on it as an unauthorised long-term loan.'

For a second the Doctor mused back on his past history, a Gallifreyan exile, a thief of time moving loosely around the cosmos, picking up and transforming the lives of countless companions along the way.

'Did you mean that thing about partying and warning?' asked Rose, her voice seeming to come from a great distance.

Recalling himself to the present, the Doctor figuratively shook his mind and came back to the moment abruptly.

'I wasn't entirely fibbing, noooo. If you ever went on a rave, then you know how the organisers get their message out to the public, the public they want to reach. Planetary parties are like that too.'

'Because - ' began Rose, before being cut off.

'Because for a planetary party the event has to be massive, huge, overweening,' raced on the Doctor, indicating with enormous arm gestures just how equally enormous the event needed to be.

'Because - ' tried Rose again.

'Yes, because only an event that big can justify sending out a signal that covers parsecs, saying "come to our liberation from evil overlords party" or "we're having a successful Faster-Than-Light pioneer party" or "we've successfully terraformed a barren world into a second home – come and christen it with us!"

With his innate sense of the dramatic, a quality that had been present in every one of his regenerations, the Doctor finished on a high note, expectantly looking to his solo audience for applause and appreciation.

'Because,' continued Rose, doggedly. 'That little green light you mentioned has just turned red.'

Undercut in terms of drama, the Time Lord whirled round and leant over the console, eyeing the small scarlet bulb with interest.

'It's turned red!' he said to nobody in particular.

'Shall I get out a posh frock?' joked his companion, at which the Doctor tapped his lips thoughtfully with his sonic screwdriver.

'One moment. That light's a push-indicator. Let's push it and see what happens.'

True to his words, when he pressed it firmly the bulb sank into the console with a positive click. Both travellers waited, poised, for an alarm to ring or a monitor to activate. A tremor ran around the control room, the time rotor juddered a little and then settled down again.

'Nothing,' said Rose, disappointed.

'Nothing much,' corrected the Doctor. He pointed to the external scanner. 'That's not Sol!'

Rose mentally translated "Sol" into "The Sun" because that's how she still categorised Earth's nearest star, for all her travels.

No, the crimson giant on the monitor was not the warm, friendly familiar sun she was used to seeing.

'Where are we?' she asked.

Instead of answering, the Doctor cradled one elbow and stroked his chin.

'Emergency transfer. That indicator shifted us forward in time and space.'

'Yes, but where in time and space?' asked Rose again.

'And why?' the Doctor asked himself.

He wasn't deliberately ignoring her, realised Rose, he just wasn't hearing her at all. Sighing, she picked up the mahogany mallet that she once dubbed the most important tool in the TARDIS and gave the control console a half-hearted whack – just enough to get her companion's attention.

Two things happened when the mallet clattered against the console: the Doctor broke out of his self-absorbed reflection, and the small red bulb popped out of it's depressed position, where it had been stuck.

Instantly, a thin metallic piping sound began to issue from the monitor speakers, with a three-dimensional waveform superimposed over the solar image, as ought to have happened - had the indicator not stuck.

'Clever girl,' praised the Doctor, possibly referring to Rose or the TARDIS or both. He eyed the now-unstuck button ruefully. 'Must remember to pick up some WD40 next time we visit your mum.'

'I didn't mean to - ' began Rose, before getting back to the subject. 'Where we are, hmm?'

Her mentor squinted at the monitor and frowned.

'Nowhere local. I don't recognise that star. Nor that sound, either.'

He went back to the central controls and carefully inspected a bank of readouts.

'About eight hundred and fifty light years from Earth. Date: ooh, not good. Not good. Four thousand two hundred and twenty.'

4220? wondered the teenager. Did that arrangement of numbers have some strange bad luck associated with it?

'The Grey Empire,' muttered the Doctor over his shoulder. 'Not good.'

'That signal keeps repeating,' realised Rose.

'Yep. Every seven seconds. Automatic distress call, at a guess.'

Alien, then, realised the young woman. If it were human it'd be in a language or maybe Morse code – if they still use Morse code in four thousand two two oh.

The Doctor stared at the repeating waveform intently. Alien, repetetive and yes, probably an emergency signal. Which would explain why the TARDIS suddenly jumped from Earth to this star system, once that emergency re-locator had been pressed. If he didn't recognise it as an emergency signal, the TARDIS did.

Clever old girl! Now let's see what we have here, he mused, switching the monitor to display the local planets and the sun. One earth-type planet, orbiting within the Zone, and half a dozen gas giants further out. The sun was a red giant – ah!

'That must be where the signal is coming from,' assumed Rose. 'The small planet.'

'I can see why they're sending an alarm,' added the Doctor. 'We didn't materialise near the source because local spacetime is being distorted by that star.'

He turned to face Rose, sombre for once. 'That sun displays all the signs of imminently going supernova.' Seeing sudden alarm on the face of the young woman, he qualified the bad news. 'That's "imminent" in astronomical terms. A couple of centuries to you.'

With a little trepidation and a lot of skill, he dematerialised and re-emerged into normal spacetime much closer to the rocky world. Sharing Rose's assumption, the Doctor rapidly scanned analytical monitors reading the world below for the distress call's source:

No visible signs of civilisation, no roads, bridges, dams, ports or cities. Only to be expected. If a civilisation had existed on such a threatened world, they'd be evacuating en masse in spaceships, or be gone already. No spaceship exodus, hence no resident civlisation. No transmissions on any radio bands, no televisual transmissions –

'Oh!' he said, surprised.

Rose was busy watching the planet scroll by underneath them, a vista of island archipelagoes and bright blue oceans, scattered small continents, a fetching covering of clouds –

' "Oh"?' she repeated. 'Oh what?'

'That signal - ' and he twirled the scanning monitor to display an enormous blue pyramid graphic set on a quivering pink plain, graduated scales circling around the peak of the pyramid. 'A Lowry piggy-back hyperspatial beam. Powerful, too. In fact powerful enough to reach Earth.'

'However, it isn't the distress signal,' stated Rose, confidently.

'No it isn't. For one thing, Lowry was a Canadian, so that makes this signal human. How did you know?'

'You said "Oh!",' explained Rose, a touch smugly. 'If you'd found the alien transmitter you'd have said "Ah!" instead.'

Tutting at his apparent transparency, the Doctor located the source of the new beam.

'Here we are. I'm going in.'

Navigating took more effort than he'd imagined, with proto-eddies in four-dimensional space making final approack difficult. A bead of sweat on his brow, he landed the timeship and heaved a grateful sigh.

The time rotor gave a final throb and sank into silence. The external scanner rotated in a full circle, showing a level landscape carpeted with grasses in shades of green, yellow and purple. Stands of trees clumped together distantly, with occasional shrubs dotted here and there. Towards the horizon the sky shaded into a darker colour, and random twinkling betrayed a shoreline and waves. Muted buzzing indicated insect life, interspersed with occasional cricket-like chirping.

To Rose, it seemed like the African savannah, just waiting for a lion or herd of zebras to appear. After the muted background of the TARDIS's aural ambience, it felt incredibly quiet.

To the Doctor, it seemed a nearly blank canvas, where the highest form of life probably lived in the seas and hadn't yet colonised the land. Largest form of land life would be arthropods, analogues of insects on Earth. What he liked to call a Quiet World – no civilisation, no technology, no large animals.

He carefully checked the atmosphere, which was passable, if a touch thin, and declared himself happy. Both he and Rose stepped outside and took a deep breath of the warm air. Long grasses waved around them in a gentle breeze that carried subtle

smells and scents, an indication that this planet was not Earth and there were no roving bands of animals about to arrive and evoke the African savannah.

Overhead, the glaring red sun resembled that seen at sunset on Earth, whilst still being high in the sky. The wind rustled leaves on a nearby stand of trees with incredibly drooping branches, creating the illusion that the trees hid watchful onlookers.

'I warn you, watch out for creepy-crawlies,' said the Time Lord. 'This planet's in a comparatively early stage of evolution. Expect insects and not a lot else.'

Skin goosepimpling, Rose nervously looked all around herself for any signs of spiders or ants. The long grasses stood up to knee-height, allowing plenty of cover for things to sneak up on her.

'And they'll probably be huge!' teased the Doctor. 'Why, there was a species of prehistoric dragonfly on Earth with a wingspan of over two and half feet!'

'Doctor!' scolded the young woman, still looking around.

'What was it called now – Meganeura Monyi. So the local – ow!' he ended as Rose convulsively grabbed his bicep.

'Oh,' he blinked and muttered, seeing what had alarmed Rose.

A huge rat, with a body fully two feet long, stood on it's hind legs, watching them from mere yards away. It had stood upright from the grasses and now looked at each in turn.

Don't make any threatening moves! Rose silently told herself. She hated rats, nearly as much as spiders. If they both remained still and silent then it might not attack them. Didn't rats always run away if they got the chance? Horrible dirty creatures!

The Doctor shook off Rose's clutch and leaned forward, hands on hips.

'Hello there!' he said, cheerfully.

The rat threw up one front paw and then it was off, racing through the grasses with incredible speed, throwing up spurts of sandy loam.

'Phew!' gasped Rose, exhaling a mighty breath. 'Ugh! I hate rats!'

'Silly attitude,' lectured the Doctor. 'Highly intelligent creatures.' He tapped his lips with the barrel of his sonic screwdriver. 'What is a rat doing here?'

'Yeah – so much for giant creepy crawlies!' added Rose sarcastically. 'Meet an escapee from the local mad scientist's lab.'

A tut was her only response. The Doctor had noticed a small metal box on the creature's neck, an artefact he could only surmise about, still - evidence that the rat had interacted with humans. Not only that, there seemed to be a regular pattern on the creature's back.

'Well, it headed towards the higher ground yonder. Let's see what it leads us to.'

There were no more giant rats. Rose did see an unidentified disturbance in the longer grasses off to their left, and gave it extra distance to ensure it remained unidentified.

'A word of warning, Rose. This timeframe is the time of the Grey Empire on Earth.'

'I heard you mention that. And "not good".' She concentrated on not treading on anything horrid, slimy and squirmy underfoot in the multicoloured grasses, also

keeping well clear of a clump of thorny shrubs. There was an equivalent here, an unmentioned fait intuit, one that she didn't fully appreciate.

'True. How to I describe it concisely? Ah – a blurb from the incomparable Philip Kendred Dick. "A skull-crushing totalitarian dictatorship". One that encompasses the entire Solar System, and nearby stars too.'

'You want me to keep my mouth shut, don't you?' blurted Rose. ' 'Cos I'll muck it up if I go yakking on.'

'Not at all,' replied the Doctor, mildly. 'No. Honest, they won't know what to make of you. Terms of reference being so different.'

Rose stopped and pointed. A big dark green vehicle was driving from higher ground to the east, directly towards them, churning up the soil as it came, indicative of high speed. It looked vaguely military, with an enclosed cab and rear body, riding on giant tracks.

'Reception committee. Shame. I was enjoying the walk.'

Rose shook her head. Trust him! She was too nervous looking out for giant spiders in the grasses to find walking entertaining.

Instead of stopping, the big tracked vehicle raced past them. Rose felt a spatter of thrown grass and soil hit her lightly as the machine zoomed onwards.

'Hey! These are only a week old!' she called out indignantly, slapping dirt from her jeans and tee-shirt. Paying no notice to either traveller, the machine raced over to the TARDIS, slowed dramatically and circled the timeship.

Montag paused with his miniature sand-spray gun, moving back and regarding the newly-flensed vehicle axis shaft. Good. Good enough. Cleared to a depth of half a millimetre, he'd done enough to ensure that the Rapid Rider would continue to move rapidly, at least until it needed another overhaul.

A tattoo of pawprints on his head made him turn, propel himself backwards on the service gurney and pay attention to a TEST rat, one nearly beserk with excitement.

'Okay!' he bawled, scooting out from beneath the tractor and into sunlight. 'What? What is it?'

"!" signalled the TESTer's signal box around it's neck. "Bad" "Strange"

Montag squinted hard at the rodent.

'Are you telling the truth? Because this doesn't sound like it.'

"Bad' "Strange" "Human" continued the intelligent rat. "Police Chamber".

That last got the undivided attention of Montag.

'What, a chamber? A Police chamber? Police? You mean the Moral Audit!'

He paused and thought hard: there was no reason for the Audit police to appear here with a portable execution chamber, surely; not this far out from Earth. 'Show me where!' he ordered, harshly, as bothered for himself as for anyone else. The pair bounded into the cab of the tracked vehicle, Montag firing up the engine even as he slid into the driver's bucket seat. The rat, Number 17 from the numbers on it's back, jumped up alongside Montag and pointed outwards. When he drove out of the camp at speed, the rat bobbed it's head and clung onto the dashboard, continuing to point to the east.

"!" it continued to signal.

Only after circling the bizarre blue object did Montag relax – it clearly wasn't an execution chamber after all, even if it did have the word "POLICE" displayed prominently.

"Strange" "Human" continued the TESTer, pointing back along their route. Montag realised that he'd just raced past two people he didn't recognise.

'Let's go back and see who's playing with disguises.'

The big green overland tractor revved up and slowly approached the Doctor and Rose, coming to a halt but with the engine still running. The cab folded itself down around the driver with a series of whines and clicks, allowing the travellers to see the giant rat perched on a seat, pointing at them.

Astonished as Rose might be at the sight of the rodent proudly sitting alongside the driver, the man looked equally astonished. His dark, bushy brows drew together in a puzzled frown over eyes wide with surprise – and a touch of fear.

'Who the snelf are you!' he asked, over the thrumming sound of the tractor.

'We're here about your SOS,' explained the Doctor. 'This is Rose - ' he indicated her, so she gave the driver a cheery wave ' – and I'm the Doctor.'

The driver looked as if he'd been kicked.

'Doctor! SOS? What the fnorp are you on about?' He looked around the empty veldt suspiciously. 'And how did you get here?'

The Doctor proudly indicated the TARDIS, to a wary cocked eyebrow.

'Looks cosy. High-speed shuttlecraft, eh?' Several long, slow, silent seconds ticked by. 'You'd better come back to Serendipity with me. Doctors and emergencies!'

Both travellers clambered up the side of the cab, Rose taking care not to get anywhere the giant rat, which swivelled on it's seat to watch her and her mentor.

'Told you they were intelligent creatures,' smarmed the Doctor. The rat bobbed it's head, squeaking. With a touch of awe, Rose witnessed "Good" and "Thanks" appear on the display screen of the metal box mounted around the rodent's neck.

Very well, perhaps the SOS is a secret communication, mused the Doctor, whilst whistling at the rat and nudging Rose with good-humoured mockery. A secret known only to the communications staff here. How do you keep the secret of a sun that might go bang, however? That's a big secret to keep.

Rose felt less concerned with internalised secrets. She tried not to look at the rat, which meant instead looking out across the savannah. More vast mats of multi-hued grasses, and odd-looking trees that displayed an un-naturally flat top, as if shaved flat with a giant razor; trees whose branches seethed with vaguely-seen creatures. Plus droning flying insects, which she treated with distaste rather than fear. She also got a good view of the perimeter wall as the tractor cruised through a giant gap cut into the landscape around Serendipity. On the outer wall the pitch was steep, but on the inner side it fell gently to the level, sandy ground within.

She blinked in surprise at the contrast to the unspoilt lands without: what lay within constituted a small village of high technology buildings and equipment, all arrayed concentrically around a vast, dark grey cavern. Radio towers – if they even used radio in the year 4220 AD – and racy-looking tracked vehicles, what looked like a tank wearing a matt-grey plastic skirt, big square dishes pointed at the skies, and a gigantic helical construction pointing to the heavens. Great cubical conglomerations of pallets, ridged and stencilled and slotted for crane deployment, covering at least an acre, lay abandoned and dirty.

'Lowry Hyperspatial Transmission Coil,' murmured the Doctor, nodding at the spiral antenna.

The tractor slowed down considerably once inside the protective wall, and given the number of people walking around purposefully who were not paying attention to road safety, Rose decided slower was safer.

Drawing up besides the giant grey cavern, the driver performed a series of checks and inputs that stopped the tractor, killed the engine and re-erected the cab. He finally turned to the travellers and stared at them.

'Time to get out,' he finally informed them. 'Can't you people take a hint?'

The Doctor shot to his feet, wearing an insincere but convincing smile.

'Serendipity! Splendid name! Quite apposite, don't you think, Rose? Come on.'

Startled, Rose jumped to her feet, cast a glance at the giant rat and jumped from the tractor. Her feet sank into an earthy loam, causing her to overbalance and almost fall, until the Doctor caught her elbow.

'Be careful from now on,' he cautioned her, all the false humour gone. 'Take your cue from me. In case of trouble, you are from one of the Rebel Colonies.'

Rose flicked errant hair out of her eyes.

'Rebel Colonist, got it. Rose Tyler, rebel.'

Behind them, the tractor driver dismounted his cab, then came over to cast a jaundiced eye over them.

'Snelf! People like you are the reason I prefer to work with pre-Cambrian shales. Follow me.'

Snelf? mouthed Rose at the Doctor, who wagged a silent finger at her in warning not to mock or talk aloud.

The driver, minus his rat, led the travellers over the well-packed ground and a field of nylon anti-wear netting. Their destination was the yawning, forbidding and uninviting cavern Rose had seen when the tractor entered the perimeter.

Interesting! was the Doctor's first analysis. He peered closely at the grim, grey walls of the cavern entrance as they marched inside.

Fusor technology, he recognised instantly. Controlled nuclear fission with no fallout or residual radiation, able to shape solid rock as easily as a sculptor worked putty. Also, incidentally, several centuries beyond current human technological achievement.

'Paleo-geologist?' asked the Doctor. He knew that the driver must be such a specialist, from the hint he'd dropped. Confirming and coercing in one fell swoop could only benefit them.

The driver didn't get a chance to answer. Three other people came up the angled entrance ramp into the structure, and all three instantly stopped to look at the new arrivals.

'Here about an SOS, if you can believe that!' snorted Montag. His mocking voice echoed around the cavern's interior.

All three women, wearing nearly-identical boilersuits, inspected the two travellers.

'Don't try to get me on your side!' blurted one of them. With that, the trio moved away, muttering amongst themselves. Rose realised they disliked the driver equally as much as they distrusted both she and the Doctor.

TWO

Rose looked at the forbidding entraceway to the bunker called Serendipity, thinking that it looked as if constructed of concrete with a plaster screed. The walls were smooth and clean, whilst the floor was slightly rough – to allow the inhabitants to keep a safe footing, she guessed. The entrance ramp went down at a shallow angle, leading into a huge, brightly-lit area, featuring a high vaulted roof. Smart-spotlights shone directly on them as they moved downwards, banishing shadows under dazzling halogen beams.

Casting an analytical eye over his surroundings, the Doctor noted the various bays and walls that divided the interior. Everywhere lay pieces of human equipment, stored, being repaired or cannibalised. An air of casual work pervaded the people diligently performing their tasks – certainly not the suppressed panic of an expedition stranded on a doomed world.

'Where's Roj?' asked the driver to a cluster of workers inputting data on a keyboard array, the input reflected back to them in a three-dimensional bubble.

'Looking at the air-con plant,' replied one of the workers, a Chinese woman who looked at the two novel travellers with undisguised curiosity. She whistled loudly, causing a giant rat to suddenly dart up at her feet. 'Take these to Roj,' she ordered, at which the rat squeaked and bobbed it's head before approaching the driver and then scurrying off again.

Unable to resist a shudder of disgust at the horrid hairy creature leading them, Rose looked about her, seeing extra screen partitions added to the original huge walls, what appeared to be a makeshift dormitory, a big, open-plan kitchen, shower cubicles, and stores. People at work casually glanced at her and the Doctor, then openly stared at them, with expressions of surprise and suspicion.The floor at the bunker's far end slanted downwards to a landing, where it turned and led to another level, beneath the first one. Onwards scampered the rat, into a bunker filled with the support equipment needed to sustain the level above, and here Rose got a true sense of the bunker's size – easily covering an area equivalent to a football pitch.

Down here the lighting levels were lower, being mainly fixed spotlights mounted on equipment, great bulky generators, a massive metal-banded water tank, colour coded sewerage pipes, and an air-conditioning unit that droned away. A knot of people were standing around this big, angular unit, checking readouts on the equipment's dials and comparing to various hand-held ones of their own.

The giant rat went racing up to one of the busy workers, stopping to tug on his boilersuit leg. The man, big and bulky with thinning ginger hair, looked down with annoyance.

'What?' he asked, irritably, before looking at where the rodent's outstretched paw pointed. 'Montag? Who the mooj have you got there!' once he resolved the faces of the Doctor and Rose.

'Hello there! I'm the Doctor, and this is Rose!' said the Doctor, loudly, sending echoes of Rose-Rose-Rose winging down the level. He wanted to take charge of the conversation straight away so he plunged on. 'We're here about your SOS message! Picked it up at a distance and we're here to help you!'

The other members grouped around Roj stopped working to look at the speaker, whilst Roj himself looked at the Doctor in stunned astonishment.

'Doctor? SOS?' he repeated.

'The distress message you sent out,' clarified the Time Lord. 'About the impending supernova? The impending supernova and your presumed evacuation?'

Now all the audience were staring at the Doctor as if he had two heads. Fortunately for clarity, Montag spoke up.

'Found them out in the grasslands. They appear to have arrived here from orbit in a high-speed shuttle. And – the shuttle is Police issue.'

An instant silence fell over the group, Montag smirking in amusement at the distress his news caused. Roj, for one, seemed to cave inwards straightaway, looking panicked and nervy the instant Montag stopped speaking.

'Police! You mean the Auditors? Moral or Political?' he asked.

Montag shrugged.

'No idea. From the look of them I'd guess they're fishing for Radix.'

'We are not police!' snapped the Doctor, exasperation shading into his voice. 'Nor Auditors, or Evaluaters, or Assessors.'

A dumpy, red-faced woman next to Roj spoke up.

'There! They've just voided any legitimate status they might have had. Now they're just nobodies.'

The Doctor remained silent for several seconds, working out the internal dynamics of the group that faced him, their likely background, and why they didn't seem to acknowledge an emergency distress signal.

Could it have been sent by a single member of what seemed to be an expedition? Without their superior's consent? That would imply a less-than-coherent management. Given the effect that the local sun was having on local space-time, there was little possibility that the unstable sun had not been detected.

'We are here specifically and uniquely to study ZLM and it's strange behaviour,' said Roj, slowly and carefully and patiently. 'Which means we did not send out an SOS message. We are here by design.'

The Doctor and Rose exchanged glances.

I know what you're thinking, the young woman thought. There bloody well was an SOS, right from here, because we picked it from orbit around Earth!

Raising a finger, the Doctor prevented an outburst of annoyance from his companion.

'Be that as it may, now that we're here, we'd like a conducted tour of your expedition's site. Quick as you like!' he added impishly, trying for a disarming grin.

Roj didn't seem to take this too badly. The grumpy, dumpy woman at his side differed, tugging him downwards by his elbow, frowning ferociously.

'Leave it, Christy,' said Roj, tiredly. 'Finish off profiling the air-con, will you?'

He led them back up the giant angled ramp, the rat scampering ahead of the group. Rose suddenly realised that the fur on it's back wasn't showing a strange, regular marking – the fur there had grown the number "17" in black, or been sprayed on via a stencil.

Once in the upper level, the controlled bustle and light seemed to perk Roj up a little. He stood taller, leading them past a group of boiler-suited, silver-gloved and masked technicians assembling shining metallic disks inside a plastic tent. Several of the technicians scowled at Roj. One waved gaily, before staring at Rose and the Doctor. Of this pair, the former struggled to make sense of the plain animosity felt by these expedition members.

They detoured into a side-bay, where a maze of erected partition walls divided the space into cubicles.

'Why don't you take the young lady and show her around Serendipity?' suggested Roj to Montag. The stocky driver shrugged, then stood back to indicate that Rose ought to move ahead of him, and they went back into the main throughway, where Montag gestured upwards at nothing specific.

'We found this place when we arrived in orbit.'

'You didn't build it?' asked Rose, looking for clarification. There had to be more with a beginning like that!

'No. Aliens did. They were here centuries ago, doing mooj-alone-knows-what and they left this behind.'

He led her past the partitions towards the entrance again and pointed to the balmy, open skies.

'This was completely blocked with earth, hundreds and hundreds of years worth. We bulldozed it clear, cleaned up the interior and set up shop.'

Easy enough to say, recalled Montag. In fact their excavation took days of exhausting physical labour, having to chase and kill dozens of giant carnivorous centipedes dubbed "sillipedes" in the dark corners of the bunker, then bringing big plant down with the heavy haulers. For convenience they'd even blasted a small lift-shaft into the lower chamber, for miscellaneous smaller cargo. The bonus was that all the construction work they would have been forced to do, erecting a campsite for over forty people, remained un-necessary.

'Montag? Who's this?' asked a woman's voice from behind them. Rose turned to see a thin, grey-haired woman looking at her with suspicion.

'Oh, hi, Dev. This is Rose. Apparently the Auditors are checking us over. This is my wife, Dev Hirscheim.'

Rose smiled regretfully.

'I'm not a policeman. I'm a rebel colonist!'

Dev looked angrily at her husband.

'What are you doing with her?

Rose rolled her eyes in exasperation. Okay, it was the forty third century, but apparently wives still didn't trust husbands! She shook her head, then brushed hair out of her eyes, only to see both of the Hirscheims looking at her with a kind of bemused horror.

'What? What?' she asked.

A compact computer sat on a low wooden desk, with a swivel chair on castors behind the desk. Roj dropped heavily into the chair, nodding to a chair of lesser status for his guest, darted a look at the computer screen and then looked warily back at the Doctor, still not seeming any happier now that he was on his own ground.

'Really, you know, Rose and I aren't Auditors.' He put plenty of sincerity into the sentence, to no avail.

'So you say. Of course, an Auditor would claim that. Claim all you want.'

'What I want, what I really want, is to discuss that emergency signal.'

'I fully intend to fulfill my contract to the letter,' said Roj, speaking to a space directly above the Doctor's left shoulder.

'Very good!' congratulated the Doctor, before leaning forward in a conspiratorial manner. 'What contract?'

The other man frowned and leaned back on his creaking chair.

'Don't make fun of me. I'm co-operating, aren't I?'

Yes, you are, mused the Doctor. Because you seem scared stiff of me. Coercion is not what I want. Co-operation is far better.

'Wait a minute – show me your forearms,' he blurted, realising a technical twist that might improve the atmosphere.

Roj patiently pulled back the sleeves of his crumpled boilersuit, holding both forearms vertical. Tattooed onto the skin were barred patches of considerable sophistication and precision.

Eureka! thought the Doctor, keeping uncharacteristically silent. He recognised the "tattoos" for what they were – subcutaneous smart patches. Date of birth, Social Insurance number, gender, sexual affiliation, employment history, credit history, permission to drive, permission to own a vehicle, permission to own a pet, permission to marry, permission to travel – all that and more would be recorded and updated on the patches.

Still silent, he rolled up his long camelhair sleeves and showed his own forearms, entirely bare of any decoration.

The effect of this simple act was dramatic. Roj leaned forward and stared in utter disbelief at the Time Lord's lack of patches, before leaning back on his chair and gulping in alarm.

'You - ' he began, before stammering to a stop. 'No patches. You're not an Auditor! Snelf, you can't even come from Earth!'

Roj's mind raced at the simple revelation. No patches. They were surgically implanted at age three, when children attended compulsory education, and to tamper with them, let alone remove them, meant Applied Cortical Conditioning.

'Rebel colonist, that's me,' assured the Doctor. 'Entirely honourable and trustworthy. Now, about that SOS …'

Several other members of the expedition came to gawp at Rose, now that the Hirscheims had loudly exclaimed about her non-Earth origins. A pair of the giant rats also stopped by to nosey, standing on their hind legs to bob and peer curiously at whatever the humans were congregating around.

"?" and "!" they signalled to each other.

Rose stared at her bare forearms discreetly, then at those she could see of the people assembling round her. Not many, given the boilersuits they all wore – aha, yes, there were the patches Montag mentioned.

'You all have these patch thingies?' she asked, and wrinkled her nose. 'Blimey! And people made a fuss about ID cards in my day!'

'Come and sit down, have a cup of neo-tea,' invited Dev, a lot kinder now that she realised her husband hadn't been flirting with an attractive stranger. 'Tell us where you're from.'

'And what the fnorp you're doing here, in the armpit of the galaxy!' added a stranger.

Immediately Rose realised this might be tricky or dangerous, taking consolation that the Doctor's warning about cultural differences should still hold true.

'Fine!' she cheerily agreed. 'What's neo-tea?'

'If you believe the packet blurb, it's a synthetic created by the finest Indian chemists,' commented Dev, drily.

'It's hot, wet and drinkable,' commented another person, their underlying tone being the complete opposite of what they'd said.

Rose found herself buffeted gently away from the wide central through-way of Serendipity and towards a huge variegated bay, where multitudinous tables sat expectantly, amidst the scatterered detritus of hundreds of meals taken there. Against the far wall stood a gigantic array of metallic pipes, struts, boxes and conveyor belts, working away at a low-level intensity.

'Our canteen!' declared one of the strangers, before realising that their solo audience didn't realise what was meant. 'Where we get food and drink for free.'

Whilst Rose managed to inculcate herself with the staff at Serendipity, the Doctor found himself considerably less popular with Roj. For one thing, the setting was all wrong, stuck in a pokey little cubicle fifty metres underground. If the Doctor were to manifest all the best and most persuasive aspects of his personality then he ought to be above ground, instead of being hindered by virtue of this giant subterranean bolt-hole. Still, he'd work with what he had – Roj insisting, with considerable puzzlement, that the mission hadn't sent any SOS.

'We're all on nine-month contracts. Invoking a return to Earth might invalidate our contracts.'

Squinting with an effort to recall, the Doctor chewed his inner lip and brought back memories about the Grey Empire. A faceless, bureaucratic pen-pushing empire – which was very big on contracts. If you upheld your end of the contract, whatever it was, then the Grey Empire held up it's end.

'Nevertheless, I did pick up a message. Possibly alien in origin. Perhaps the same aliens who built this site?'

Roj glanced up at the vaulted ceiling, thinking: occasionally you forgot your existence within a giant alien subterranean bunker.

'I doubt it. They were long gone by the time we arrived. Radio-assay of the bunker walls shows they left - '

'Eight hundred and fifty years ago,' muttered the Doctor (ignoring Roj's expression of surprise and acknowledgement). Pretty obvious, really. The signal took that long to travel to Earth from this system, travelling at the speed of light. Since he'd never detected it before, then it had only just arrived in the vicinity of Earth. Hence eight hundred and fifty years ago.

'Yes. Yes, and nothing remained intact. Oh, apart from the Dyke, that big wall around the site. This bunker, too, and two much smaller ones to the north.'

'What were they defending against?' asked the Time Lord, curious. After all, underground bunkers, and defensive earthworks –

Roj shrugged.

'Nobody can really say. Oh, there are the odd hostile life-forms, like the sillipedes, but the local fauna can't metabolise human protein.'

He hiked up the leg of his boilersuit to reveal a set of purple weals.

'Bitten. One of the sillipedes got me, the little fnorp. Then it went into convulsions. So the aliens weren't trying to defend against the locals.'

Going off at a tangent, the Doctor tried another conversational tack.

'So. Both you and an alien expedition came here. You are studying the local sun. What were your predecessors doing?'

Inwardly he felt almost certain that the aliens, whoever and whatever they were, had arrived here with the same intent as the humans who came later: to study a sun on the verge of going supernova.

Roj confirmed this in a few words. Not that the alien's presence had even been suspected originally, and here the mission leader waxed at length on the astronomical process that led to his arrival here, with his colleagues.

The star they were studying had been dubbed "Zai Long Di Yan Jing Xia Mian", detected by a long-life Chinese survey satellite a century before. The star wasn't visible from Earth, since two nebulae prevented any of it's light from reaching human telescopes. It had taken the Chinese satellite fifty years to move out of the radio-shadow of the interstellar gasses, and send it's message back to Earth via a Lowry signal. The witty Chinese, realising that their new star would be in the constellation of Draconis – if they could see it – gave it the title "Under the Eye of the Dragon". Zai Long Di Yan Jing Xia Mian was far too long for everyday use, and it rapidly got shortened to ZLM. The planet being used as a base of operations was ZLM Prime.

ZLM itself exhibited unusual behaviour. It periodically flared, in the manner of a non-radial pulsator, on a regular but extremely long period of five years, making it entirely dissimilar to the typical alpha Cygni variables that astronomers were familiar with. It seemed unique, and it's behaviour might very well be related to the phenomenon of supernovae. Consequently, given a priceless opportunity to study such a star, an opportunity that might not occur again for centuries, a mission had been assembled for that very purpose.

However, compiling a mission crew who would willingly sit on a planet circling a sun that might go supernova at an indeterminate point in the very near future had been difficult. In fact, very difficult. Almost impossible. Almost – but not quite.

In the automatic canteen facility, Rose sat at a table, with an audience of half a dozen people who were either off-duty, on-duty but skiving, or simply nosey. She already knew Montag and his wife, Dev. Arkan and Wodie Wolff also introduced themselves, together with Dan and Beatrice. The latter got a frosty look from a couple of the others, for no obvious reason.

'Honestly, we came because of the distress call,' insisted Rose, sipping the almost-like tea drink.

'Tell us where you're from!' asked Dan, a small dapper man who managed to look good in the baggy universal boilersuit. He spoke with a pronounced French twang.

'Yeah,' agreed Beatrice. 'You can speak freely here, you know. No Security listening. That's why I like it, you don't need to look over your shoulder.'

Montag looked glum, and Dev shot an angry glance at the woman, muttering inaudibly.

'I come from,er, London,' began Rose, slowly, wondering how long she could keep up the pretence of being an interstellar rebel. Indeed, simply mentioning "London" raised eyebrows.

'London?' repeated Arkan, a swarthy-skinned man wearing a big grey moustache that contrasted with his shaven head. 'Surely not! The place that used to be the capital of – what was the place again?'

'England,' supplied Rose, beginning to feel a bit creeped-out at the question. 'Well, where are you from, then?' she asked, trying to deflect attention with questions of her own.

'Northern Heavy Industrial Zone,' answered Arkan. 'Leipzig,' he added on seeing Rose's incomprehension. 'Leipzig is still standing, unlike Lunden, which got demo'ed way back when The Administration was beginning.'

"Demo'ed". "Demo'ed" sounded suspiciously close to "demolished". London demolished? An entire city?

Wodie elbowed her husband.

'Ark! Obviously her colony adopts the old names, ones they used before the Grey Empire.'

Arkan winced a little. His wife tutted at him again.

'You old woman! There's nobody here to spy on us. And everybody calls it that.'

'Not in public,' said Beatrice. 'Although you're right. As I said, that's why I like it here.'

'Shall I?' asked Dan, getting up and collecting the used cups.

'So – you're French, right?' queried Rose. Really, she wished the Doctor had briefed her a bit more about this culture!

Dan whistled in alarm, and his plastic cups rattled on their saucers while he carried them over to the washing machine.

'Snelf! Girl, you really are a Radix! That sort of language earns you a trip to the Re-education Camps back home. Western Agricultural Zone, young lady, Western Agricultural Zone.' The cups chugged into the washing machine, which splashed and slurped loudly, emitting steam. 'More tea, anyone?'

Feeling that she had managed to accidentally acquire a convincing background story, Rose assented, looking around the others at her table.

'Yep. Well, it gets my vote!'

Oh dear, she thought, as people looked at her once again, very intently. Dan gave a low whistle.

'Did I call you a Radix, Rose? I take it back. You're a positive Freethie!' and he rolled the "r" in "Freethie" with Gallic relish.

A Freethie. From people's attitudes, Rose couldn't tell if that was good, middling, or downright dreadful.

Before she could get herself into more trouble, a piercing electronic trilling cut across their conversation, indeed across all activities in the underground complex. The listeners at her table sighed and nodded to each other.

'Shift change,' explained Montag. 'I'd better get to the radio shack.' He gave his wife a goodbye hug and pointed at Rose. 'Watch out when talking with Roj. You'll give him a heart attack, and the Doc might have trouble coping.'

Arkan and Wodie had other work to do. Dev collected up the dirty crockery and cycled that lot into the washing machine, too. For want of anything better to do, Rose followed, hands stuck into the back pockets of her jeans.

'I notice people seem to not like Roj very much,' she began. Dev snorted as she pressed buttons on the machine.

'Spineless plabby! Really, if The Administration told him to kill himself, he'd do it, that one. No backbone. And he's a volunteer, like that Beatrice Von Schoonmakker.'

She imbued the word "volunteer" with considerable venom.

'Oh! So you didn't all volunteer?'

Dev turned back to the teenager, angrily.

'Volunteer? To come here, ZLM Prime, a planet dangerously close to where the Sontarans and the Rutans are fighting? Under a sun that could explode at any moment? Away from anything remotely approaching civilisation?' She held up her forearms and displayed the smart patches. 'These are useless out here, there's nothing to interact with. I'm just like you in that respect. Volunteer!' and the middle-aged woman shook her head.

Realising that she'd trespassed on sensitive ground, Rose made apologetic noises, not really knowing what to say. Fortunately for her, the Doctor came striding into the canteen area, looking as if he owned it.

'Hello there, Rose. Chewing the fat, are we?'

'I was just leaving,' fibbed Rose, walking over to her mentor.

'Let's take a little stroll outside,' he said, nodding to the entranceway. They climbed outside, taking in the bustle and activity of people driving or working under the light of ZLM, which now neared the horizon.

'Why didn't you tell me more about these people!' whispered Rose, annoyed that she'd been so out of her depth. 'They think I'm a – a Freethie.'

The Doctor laced his hands together behind his back and pushed himself up on tiptoes several times.

'It's slang for "Freethinker". A whole lot more serious than a Radix – a radical.' He glanced at her. 'I can't educate you about an entire culture in a few minutes, Rose. You've got to learn to pick up information and present yourself intuitively. You seemed to have managed that okay.'

Rose shrugged.

'They think I come from a planet called "London". Anyway, what did you want me out here for?'

'Background information. It seems that this expedition had severe personnel problems before it even left Earth.'

He filled in what Roj told him. There were only fourteen volunteers for the distant, dangerous and dispiriting mission, leaving another thirty needed. So they recruited criminals, people with relevant disciplines, the closest to those needed. He laughed at the expression on Rose's face.

'Not criminals of the kind you're thinking about! These are Moral or Political offenders. They said or did something that The Administration didn't like. Now that they're out here, the three different factions look down on each other.'

'What crimes did they commit?' asked Rose, now starting to understand why Dev had been so angry.

'Unlawfully getting pregnant. Saying derogatory things about The Administration. Failing to report another person for saying derogatory things. Illegal use of non-sanctioned swearing. Practicing a proscribed religion – which means all of them.'

The young woman shuddered.

'Blimey! What a miserable place Earth must be! And if Roj is a volunteer that explains why so many people looked so annoyed with him. Dev called him spineless.'

She got a cool look from the Doctor.

'He spent eight weeks in a Re-education Camp for saying the wrong thing to a person he considered a friend. Roj, Rose, is not these people's problem.'

'Who is then?'

'The spy that The Administration has undoubtedly placed in this team.'

THREE

Roj Taylor idly pecked at his pulp notepad with a stylus, thinking hard about the ZLM mission's most recent arrivals.

Initially, he'd feared that they were from Moral or Political Audit, The Administration's police arm, come to visit the mission. Why the Grey Empire would send a police team over eight hundred light years to inspect a mere handful of scientists escaped him. They might have done so, and this Doctor and Rose Tyler might have been such, were it not for their lack of applique biometric technology. That alone meant they weren't police.

So, what were they? That ridiculous story about an emergency signal simply didn't hold water.

'Roj?' crackled a small speaker set into his desktop. 'The Sun Gun One team are ready for departure. Is it okay to give them Order Start Go?'

'Go on,' he replied, mechanically.

He was determined to fulfill his own contract terms to the letter, since that would get him tenure back at Bristol University. The Re-Ed sentence had gotten rid of the "Political" label, even if it meant his academic position temporarily fell into the abyss.

' "The Administration! What a joke!" ' he muttered, those same five words that had given him nine months of mixed terror and bitterness. When he got back Simon Armstrand would inevitably suffer a fall down a flight of stairs, the treacherous backstabbing mooj, oh yes indeed.

Enough of that! he sternly lectured himself. Back to the present and what was needed there. Those two new arrivals – split them up, keep them under observation, see what they really intended.

There was always the faint possibility, he mused, that one of the warring factions only a few hundred light years further into the galaxy had decided to stir the pot. The Rutans were past experts at infiltration and sabotage, and the Sontarans could bend minds into slavish obedience, and both were to be feared – even if humanity had suffered little contact with them yet.

The Doctor and Rose sat on a comfortable perch over the Serendipity bunker, where centuries of loam and grasses created a well-padded natural sofa. A sofa thirty metres square, if one cared to measure it.

ZLM itself had begun to sink towards the horizon, casting long, bloody shadows within the circular perimeter defined by the giant encircling wall. The previous activity within the site declined, apart from the hover-skirted tank, which revved it's engines thunderously, threw up a positive pillar of dust, then acclerated out of the site, headlights casting solid cones of bright yellow light into the gathering gloom.

Slowly and softly, other lights mounted on brackets set atop the various fixed positions in the camp began to glow, until discrete pools of light illuminated almost the whole base.

With darkness came chittering clouds of insects, that avoided the lights. Every so often a larger object with the rakish lines of a fighter jet came swooping in amongst the foggy masses of buzzing arthropod-analogues, disrupting them.

'Interesting. Archetypal predatory behaviour,' muttered the Doctor.

'What do they need a tank for?' asked Rose. She got a blank look in return. 'That thing, like a cross between a hovercraft and a tank.'

She wasn't asking because she wanted an answer. The Doctor was already deep in thought over where they were, and the non-existent SOS call, and probably the big alien underground parking garage they were sitting upon. No, she wanted him to acknowledge that she was there, or he'd forget and sit up here all night.

'Night here lasts twenty hours, you know,' he said without prompting, making her stare at little. Had he guessed what she was thinking?

In fact it was a conversational gambit, a facet of the Doctor's ability to simultaneously sustain two entirely different trains of thought without compromising either.

His main focus, what really came down to the reason they were there at all, was that supposed SOS call.

There was no denying that it existed. The TARDIS didn't journey across space-time on a whim. Ergo, there had been a message. The human mission here categorically denied it had been sent by them, and from the feedback Rose passed on to him from her interaction with the staff in Serendipity's canteen, there wasn't any possibility of a clandestine communication.

Very well, he needed to return to basics and check quadronometrical sources.

Beneath all that, he had a feeling, nothing more, that there was something profoundly wrong here. Wrong about the mission, wrong about this enormous fortification they sat on, and wrong about the planet.

'Hardly a tank,' he replied, a second late. 'Probably a mobile multi-sensor array with a rotational base assembly.'

'It looked like a tank! Like one of the models Micky used to build when he was in the wargaming club at school.'

'Wellll, yes, it probably would, to you, Rose. This culture has stamped out war amongst humanity. It doesn't need tanks. Morals, a conscience and liberty, yes, but tanks – no-no.'

To get a quadronometrical assay, he'd need access to the base's communications equipment. Trailing back across kilometres of grassland to the TARDIS was a complete non-starter, and he'd be running madly around the inside of the timeship doing an Olympic sprinter impression, trying to operate the consoles on his own. Here in camp he'd have a better chance to get more background information, quite besides only having to pace like a county track-meeting runner.

Behind all that, the other why's came crowding in. Why were there alien remnants here? What were they trying to study? And why did they leave?

A penetrating hum, detectable in the lower intestine, wisdom teeth and the mastoid process, began to pervade the camp. Rose winced and swallowed.

'Ow! What's that?'

'Hyperspatial transmission coil,' declared the Doctor, not looking at all bothered and instead staring intently at the mounting that held the giant helical aerial. 'That Lowry! Genius! Proof that the Canucks aren't just North North Americans – no, no, that's too terracentric.' He turned back to Rose. 'The original set-up sent out X-rays that were fatal to any unshielded humans within a kilometre.'

'Don't worry!' he hastily added, seeing his teenage protégé turn a fetching shade of green. 'By 4220 AD they have the emissions tamed. Still, it gives me an appropriate focus.'

He looked across the encampment at the pressed-steel plank hutment that housed the HTC equipment, calculating. The senior administrator here, Roj, would send a party or parties to keep a weather eye on Rose and himself and prevent either or both from interfering with the mission's running. Poor fellah, he'd no idea what to make of either of them.

'Hi!' called a chirpy male voice. The owner came into view as he clambered up the earth that covered the bunker's upper surface, a thin, lithe, large-eyed young man. 'Roj sent me to find you. He wants to make sure you both stay out of mischief.'

'We weren't in any,' offered the Doctor, teasingly.

'There's not much to find out here on ZLM Prime,' agreed the youth, throwing himself down on the ground alongside Rose. 'Dull as ditchwater.'

'Rose,' said the young woman, extending her hand.

'A rose? No, it's a hand,' replied the other, uncertainly.

'No physical contact unless between consenting adults,' recited the Doctor. 'People don't shake hands.'

'Oh!' blurted a surprised Rose. 'Sorry. My name is Rose. Rose Tyler.'

'Aha. I'm Eric French. Pleased to meet you, Rose Rose. So, you two are from one of the rebel colonies, eh?'

They certainly had an efficient gossip system here! mused the Doctor.

'A long way from anything you're familiar with,' he replied ambiguously.

'How come you're called "French"!' asked an indignant Rose. 'That man Barthelmy bit my nose off for calling him French.'

Eric winked.

'Great, isn't it? Ticks The Administration off no end, but they can't do anything about it, family surname for centuries. Hey, you two aren't from Magellania, are you?'

Mag-what? mouthed Rose at the Doctor.

'Ah – refugees from the Grey Empire founded their own pocket culture in the Magellanic Cloud several centuries ago. No, Eric, we're not from there. Sixteen thousand light years is too far to commute.'

The young man seemed interested in the existence of a genuine rebel civilisation, perking up and paying attention.

'I'm from London,' explained Rose. 'Nothing like as hi-tec as your world, although we have lots of things you don't.'

The Doctor instantly saw a window here. Handsome young man, attractive young woman, lots to talk about, no common ground hence even more to discuss, an opportunity to check out the HTC system. With cat-like stealth he left so silently and subtlely that it was a full five minutes before either of the two young people deep in conversation realised that he'd gone.

The scattered lighting in Serendipity Base managed to provide him with enough shadow cover to move discreetly – that was the word and behaviour the Doctor wanted to manifest, discreetly, not sneakily or covertly; discreetly – over to the Lowry signal station.

Before getting anywhere near there, in fact whilst still skidding slowly down the canted side of the Serendipity bunker, he caught sight of an interesting feature of the base layout, a detail he didn't think came from human design.

Once outside the Lowry communications shelter he paused to look at the giant aerial overhead, now silent, it's infrasonic spillage stopped again. The station itself had been built of steel planks overlaid with a covering of extruded plastic sheeting and looked curiously like a child's construction set simply enlarged.

Opening the hermetically-sealed door, the Doctor stepped inside and into an arena of forty-second century technology. Outside you could have been on Earth, any date from the late nineteenth century onwards – whereas, inside: there were suspended motile hologrammatic displays, wrap-around thin-film consoles, ghostly virtual interactive control boxes, modular power attachments, modular drivers, modular plug-in boxes for biometric access, all stacked and arrayed on three sides of the room.

There were two people on duty in the station, both of whom looked up in surprise from their card table.

Vingt-et-un, recognised the intruding Time Lord. The male player was dark-skinned, with a neatly-trimmed goatee and a small blue-and-white glass bauble dangling from a necklace. His female opponent, who clutched her cards close to her chest, sported red hair and freckles, green eyes and had drawn a harp on her boilersuit breast.

'Salaam aleikum,' nodded the Doctor. The man's jaw dropped. 'Slainte,' and the woman's jaw sagged also. Seeing an empty case propped up against the station wall, the Doctor pulled it over to the table, seating himself upon it as if already invited.

'Hello there!' he brightly began.

'Vasaleikum salaam,' replied the man after a pause to gather his wits. 'Who are you? Not that rebel people have been going on about?'

'The very same!'

'How did you know I was Moroccan?' asked the man. 'You rebels don't have ESP, do you?'

The Doctor shrugged nonchalantly.

'Your physical appearance, melatonin loading and tonsorial categorisation. The French card game, retained in Francophone ex-colonies, typically along the Maghreb litorral of North Africa. Also, the eye of Allah that you have on your necklace.'

'It's a – it's abstract!' blustered the man. His only reply was an ostentatious wink from the Doctor.

'Do you speak – er – Gaelic?' asked the woman, well aware that any communication not in officially-approved language could get one in very deep, hot water.

'The odd word or two, purely for the craic.' The Doctor pointed at the drawing of a harp. 'Bordering on political ideogram, you know.' He put his hands behind his head. 'What do they call Ireland now? "Peat-Mining Facility One"?' and a tone of harsh contempt rang through his words. 'Land of poetry and music reduced to that. Hah!' His face twisted in a sneer for a split second.

There was an element of flattery in his speech, combined with genuine distaste for the relentless, homogenising bulldozery of The Administration. To get his way he needed to butter these two up at least a little, and if he sounded sincere then his flattery would be the more effective.

'I'm the Doctor,' he continued. 'Doctor – ah – Doctor John Smith.'

'Amir ibn Hassan,' replied the man, bowing slightly from the waist, a tricky feat whilst sitting down. 'Expedition specialist in quasars.'

'Shona McIlwain,' smiled the woman. 'I have a library qualification in Categorisation.'

Neither discipline really relevant on ZLM Prime, cogitated the Doctor.

'If I may venture a question – why are you on an expedition that doesn't require your abilities?'

'Contract,' replied Amir. 'Serve my time here, all criminal charges dropped.'

'If I fulfill my contract, I get the Political coding removed from my Employment History,' beamed Shona.

For a moment as brief as thought can be, the Doctor pondered about the sheer incongruity of the mission personnel matched versus the actual mission itself: The Administration had to be stretching when it conscripted such blatantly unfit personnel for such a scientific endeavour.

'And what might you be here for, Doctor Smith?' asked Amir. 'A rebel from the lost colonies, here with your assistant. About an emergency signal nobody here ever sent.'

The tone was mild and unremarkable, but the question nevertheless retained an underlying and pertinent sharpness.

Seeing an opportunity, the Doctor dived in.

'Quite! Roj was absolutely insistent that nobody here had sent out any kind of distress signal, and I believe him.'

He allowed his attention to wander, looking at a bank of wrap-around consoles that flowed with atmospheric thermal data. Not to be too picky, but the mean diathermals seemed to be a little unsteady, baryspheric criteria for the upper tropospheric layer shading into unusual –

Shona waved a hand in front of the lanky intruder, who had lapsed into a silent reverie. She'd heard all the rapidly-generated rumours about a stranger, who might not be from Audit, or who might be.

'Hello? So we didn't send the message. Who did?' she asked.

The Doctor looked at her with eyes that peered far deeper than human eyes ought to.

'That, Shona, is exactly what I wanted to see you staff about. That message isn't human in origin.'

Amir nearly fell off his sculpted ergonomic stool.

'Not human!' He glanced worriedly at Shona. 'Do you mean the Sontarans or Rutans might have sent it?'

He didn't say so explicitly, but the feeling that ZLM Prime was far too close to the Debatable Zone came across strongly.

A decisive shake of the head from the Doctor.

'I would recognise their signal architecture straight away. No. This is alien, and by virtue of Occam's Razor, it had to have been sent by the expedition that preceded yours.'

Not to mention that those two alien races would, as a matter of course, have secured the surface of ZLM Prime and either exterminated, enslaved or imprisoned the human expedition members.

'That's impossible!' chirped Shona. 'There aren't any aliens left here. Our spaceship scanned the whole planet from orbit when we arrived, just to make sure.'

Reflectively, Amir twisted the blue bauble on it's chain.

'Not only that, all the equipment they'd left behind was completely junked. Eroded or destroyed by the elements after eight centuries. It's just not possible – not – what - what?' he asked, slowing down as he witnessed their strange visitor pointing silently at the roof.

'What I would like to do – with your permission, of course – is to use the Lowry coil to attempt a little quadronometrical surveying.'

Amir blinked in kinetic surprise.

'Quadro – are you serious? There's trigonometry, and calculus. I've never heard of "quadronometrical"!'

'So there are forty-four of you. Doesn't seem that many on the site,' commented Rose, turning slowly to look eastwards, over to the far distant ocean. She was trying to feign nonchalance, keeping Eric from worrying about the Doctor's absence.

Eric himself was more bothered with this enigmatic, unguessable woman from the incredibly exotic location of a Lost Colony, rather than the stranger whom she came with. She looked nicer, too.

'Forty-four in total, although there's never that many here at any one time. The Sun Gun goes off on a big geological and astronomical sweep all the time, and that means four or five people off with them. Then there's the Baby Bunkers. Two people in each of those. Even for the people supposedly here, there are jaunts into the middle distance for geology or botany.'

'What's your field?' asked Rose.

'I'm not finished yet, but I'm studying Petroleum Geology at Aberdeen. If I last out the nine months here I get one hundred and twenty course points. A two-two before even sitting the finals!'

Rose stopped still mentally, taking a second to sit back and regard the landscape laid out before her. The Doctor, on countless occasions, had warned her to pay attention to the environment and establish a background information baseline. What was there to help her here?

As she cocked her head to one side in a not-very-successful attempt to seem wise as an owl, Rose noticed an appropriately roseate gleaming to the east. When she turned rapidly to Eric, she caught an equivalent glow over to the west.

Eric answered her question before she even managed to encapsulate it.

'Oh, those are the Charcod fields. They tend to catch the light at this time of the evening.'

'Very romantic!' jested Rose in a murmur, looking at her chaperone. Eric blushed as red as the Charcod fields themselves.

'Ah – yes. The Charged Couple Devices. Ancient design, but robust and easy to create in large amounts. You may have seen some of the mission staff creating them inside Serenity bunker.'

Rose recalled the people carrying out a Dada boxing match inside a giant transparent plastic bag, whilst still managing to swear at Roj. Or at least most of them had been hostile; one or two didn't mind the mission's leader. She realised that creating the Charcod technology was one of the chores that came with the mission on ZLM Prime.

'What are the "Baby Bunkers"?' asked Rose.

Eric slapped the earth under him.

'Much smaller versions of this one. Basically just a big room aboveground and a similar sized one underground.'

Rose gazed out over the lengthening shadows, noticing occasional diving creatures darting in the dusk. She could feel Eric's eyes on her.

'Beautiful, isn't it?' he ventured, after a long silence. 'I'd like to stay here

longer if we could.'

This sentiment caused Rose to roll over on one elbow and stare at him.

'Are you making a pass at me? Because - '

'No!' gasped Eric. 'No, that's not what I – no, I meant I won't be happy going back to Earth.'

Rose laughed at his sincere embarassment, then felt guilty and slapped him on the shoulder in a physical apology.

'Sorry to leave here? Why? The sun's going to explode!'

Rolling his eyes ruefully, the young man shook his head.

'Going back to a great, grey housing project, studying in a big anonymous college, living in a gigantic drab city. No seasons, no freedom, nothing green or growing outside the bottle-parks, nothing except your fellow human being, and that in large numbers.'

Her curiosity picqued, Rose just had to ask the next question.

'Are you one of the criminals or volunteers? I can't tell from just looking at people. Don't worry, I won't judge you. I know plenty of criminals already,' and her mind flicked back to that moment inside the TARDIS when the Doctor revealed himself as a car-thief of the far distant future.

Eric bit the inside of his lower lip.

'I'm a criminal. I got drunk.'

Rose waited for the rest of his confession. And waited, and waited.

'Is that it?' she asked. 'I expected a punchline.'

A piercing shout from the compound caused both of them to abruptly turn.

'Eric!' came the pealing call. 'Eric! Are you there, you plabby!' Before either could answer a tall, dark haired young woman came jogging up the slope of Serendipity's bunker. She looked at Rose and Eric with what seemed like detached amusement.

'Ah. Yes. RoseRose, please meet Hypatia French.'

Rose rolled off her elbow and stood, feeling cramp in her joints.

'Pleased to meet you! I've been talking with your husband about the compound and personnel. The Doctor and I - '

She stumbled to a stop whilst Eric waved his hands frantically and Hypatia bit her lip in sardonic amusement.

'Actually this is my sister, RoseRose: Hypatia. Can you two say hello without spitting venom?'

The two women looked at each other for a split-second, before turning back to the hapless student.

'Are you implying that I hate all other women on sight, Eric?' asked his sister.

'Why would I dislike your sister, whom I've never met?' asked Rose, before bursting into a fit of giggles. 'You're just too easy to wind up!'

Snorting in disdain and disgust, Eric stood and eased life back into his cramped limbs.

'Hey – where's your friend gone?' he frowned.

Amir felt his head spinning. He had a degree in astrophysics, and tensor calculus or prime number theorems were old hat to him, but really – four-dimensional mathematical derivations of notional spline co-efficients used to interpret radiated EMR transmissions! He didn't even know if that were possible, not even after the Doctor's bland assurance that they were.

'I didn't understand a single word of that!' whispered Shona to him whilst the stranger took a long, slow tour of the shack's various technologies.

Feeling muddy and slow of mind, Amir looked back at her.

'Nor did I. And I should have. Hey – don't touch!'

The tall stranger didn't actually – physically - contact the insubstantial controls for the Lowry coil. Instead he stooped and squinted at them, lips moving silently in a pattern of mnemonic resonance. Whilst Shona blinked in surprise and Amir shook his head in puzzlement, the stranger whipped out a notepad, to begin scribbling on it with what looked like a pencil.

A pencil? wondered the Morrocan. A pencil! No – must be a replica, what with graphite and wood costing what they do.

He turned on his seat to follow the Doctor moving and scanning different readouts, nodding quietly or harrumphing! in implied disagreement. The intruder went back and forwards over the banks of thin-films, muttering quietly.

'Thank you for your co-operation,' offered the Doctor, before leaving the communications hutch. The baffled pair let him leave without comment, their silent and telling expressions being comment enough.

Before heading back to the bunker he detoured to the eastern corner of the compound, to inspect a small feature only visible when the light was in the right position. Relatively small, he corrected himself. Relatively small and not visible to anyone not knowing where to look or not looking closely or not looking from an elevation of twenty metres with the sun and shadows playing a very specific set of tricks on the landscape and visual perception. He paced the site, then used his sonic screwdriver, looked at the heavens and cradled one arm in another, reflectively.

Things are coming together, he realised, not happy that his subconscious had been working away at the matter on hand without his realisation. Coming together and not in a good way. Where can I get hold of a Geiger counter?

The Geiger counter wasn't difficult to find.. No, the real problem was getting permission to use it on the site, since the mission personnel firmly believed that they had eliminated all possible sources of threat to the settlers.

FOUR

'So you discovered a small crater. I applaud your diligence. Now, Doctor, if you don't mind, I really do have better things to bother about.'

So spoke the expedition's second-in-command, Cholon Khongordzolny. He wore a self-focussing zoom microlens over his left eye, and a prehensile surgical gauntlet on his right hand. The geared-down blades and pincers twitched sympathetically over a partially-dissected sillipede, which lay on a white plastic tray, oozing disgusting fluids.

Rose, flanked by Eric and his sister, looked at the pried-apart giant insect with all the relish of a relative inspecting a morgue. The creature looked worse dead than it did alive. Thankfully the airconditioning removed any unpleasant smells instantly.

'Not just a small crater. There are traces of radioactive isotopes in there, inside a smaller version of your so-called Defensive Dyke.'

Cholon, whom everyone called "Mike", wrinkled his nose.

'A radiological event? We didn't discover anything setting up Serendipity Base.' His voice this time was musing, not dismissive. The Doctor had approached him on learning that Roj was sleeping and most definitely not to be disturbed.

'The count is low,' continued the Time Lord. 'About what you'd expect after a period of over eight centuries. Still higher than the background. I suspect if you dug down you'd find a radio-glass residue. What they used to call Trinitium.'

Mike dialled up another expedition member on his wrist-phone. The rats were also sleeping and not to be disturbed, apparently. He sighed; the rats were supposed to be the fallback system when the wrist-phones didn't work, thanks to atmospherics.

'Friday? Can you and Claire come over to Biology bay? Thank you.' He pointed a monoplanar scalpel at the Doctor. 'As I told you, I'm busy. Friday and Claire can help you check out your crater. Sorry I snapped at you to begin with.'

'I forgive you!' replied the Doctor, cheerily and very nearly sincerely.

Claire and Friday Walsall were two pert, freckled sisters, speaking with a Midlands accent, and part of the expedition because they had been agitating on campus for female equality. They bemoaned the lack of boys, the lack of technology, the lack of pills and the lack of entertainment. All this in thirty seconds, making Rose stand back and try to stop laughing at their volume of speech.

'Follow me,' instructed the Doctor. He led the party of five out of the bunker and across the compound, over to where the bulky ranks of cargo pallets sat in dark, sullen rows. One pallet sat on the barely-perceptible rim of a shallow berm, crushing into the circular structure. Light from the angled spotlights filled the dip with shadow.

'Look at this depression. This is the signature of a fusion-engined shuttle taking off, and taking off in a hurry. Erosion has filled in most of the area blasted out, and the outrigger's traces are long since gone.'

Mutual glances of incomprehension or disbelief were exchanged between the expedition members. Rose nodded, convinced that if the Doctor said, then it was so.

Well aware of the scepticism around him, the Doctor picked up the miniature Geiger counter, no bigger than a watch. He scouted it over the soil surrounding them and the device made a ticking sound, a slow electronic cluck.

'The background count,' he said, then repeated his action over the slight depression. The placid electronic cluck instantly accelerated into a frantic beeping.

'Fusion engine trace,' finished the Doctor, twisting the Geiger counter off with a triumphant snap.

Friday measured the diameter of the affected area with her palms, then stood back and pursed her lips.

'I know what you're thinking,' beamed the Doctor. 'Fusion boost technology, emergency jump start escape mechanism, far in advance of human technology.'

Friday gave him a sly shake of the head.

'Uh, no. What I wondered is how you knew this was an escape shuttle. Being that it was over eight hundred years ago.'

Claire elbowed her sister in her ribs as a caution – this man might be an Auditor, after all.

The Doctor tapped the side of his nose.

'Logic. If this was the trace of an atmosphere-capable large capacity vessel, there would be multiple craters. Only one crater, ergo a smaller shuttle vehicle.'

Friday had been thinking.

'Given the area of ground affected by the supposed fusion torch these aliens were sitting on, I calculate that the shuttle is about one hundred and fifty metres tall, massing about five thousand tons.'

Not bad! thought the Doctor. His own estimate ran to a hundred and seventy metres but only four thousand five hundred tons.

'Is any of this important?' asked Eric, swatting at nocturnal insects. 'I'd like to get back to my luxurious cubicle and my sumptuous bed.'

Is it? enquired Rose by wrinkling her eyebrows.

'Yes. Er – I can't quite put it all together, not yet, but it certainly is important.'

Eric shrugged, drawing a sharp retort from the Doctor.

'Eric! You have evidence of a hurried departure, an abandoned bunker and a distress signal. Your mission here has blindly ignored anything but what they have contracted to observe. There are elements of a disaster in the making.'

The young man snorted in disdain.

'Yeah, yeah. Are you two coming back to the bunker to catch zeds? 'Cos I'm bushed.'

Adopting a stern pose, hands on hips and shoulders cocked backward, the Doctor pointed at the teenager.

'Good idea. Let's get a nightcap!'

An hour later, Rose, Eric and the Doctor were alone in the canteen area. The autonomic catering plant could provide a convincing substitute for cocoa, and the threesome sat over a collection of empties.

'Let me sum up, Doctor,' yawned Eric. 'You're worried. Worried, without any concrete reason.'

'You must think I'm a fearful old bore,' grinned the Time Lord. 'Danger! Danger, Will Robinson!' he tried.

Rose nearly spat cocoa across the table at the pop culture reference.

'How can I put it, Eric? Things here are more strange and convoluted than you imagine. Than I imagine, really.' The Doctor stretched the kinks out of his back. 'And now I need a period of repose.'

Rose left the Doctor to snore away on his camp bed, since she felt in dire need of a shower and clean up. After a long soak under the spray heads of the shower unit, she emerged to find a new boiler suit laid out on the floor in place of her dirty Earth togs. A single giant rat, towel draped over one paw, bobbed and pointed at her.

"New" it signalled. "For" "You".

Despite herself, Rose found it in her to nod and partially bow to the giant rodent.

'Er – thank you. Thanks.'

The giant rat bobbed and nodded at her, and then it was gone.

Well, she mused. They were polite giant mutant intelligent rats, at least.

A penetrating whine pitched to at least fifty decibels brought her awake the following morning, jerking upright on her flimsy campbed.

'Hey-what-say-what,' commented the Doctor, playing with what looked like a yo-yo and sat opposite her on his own bed. Alongside their blank-walled cubbyhole, unseen, other expedition members variously yawned or cursed themselves awake.

'Yawning morning,' riposted Rose, doing just that. 'I feel rough. We didn't drink any alcohol last night, did we?'

Her companion shook his head.

'No, not at all. You're just experiencing the after effects of a thirty two hour day. Circadian rhythms take a while to compensate.'

Warily, Rose looked underneath her bed for signs of rats.

Nothing there. Good! The day could begin.

'They're used instead of primates,' guessed the Doctor. Rose darted a guilty look at him, feeling absurdly anthropomorphic.

'I'm sorry! It's just – well, you seem them round the estate in wheelybins or sewers.'

Wagging a finger, the Doctor carried on.

'The higher primates are as rare as pandas in this time-frame, Rose. The TEST rats are a variety of engineered spanner, if you like. Useful, common, not worth worrying about.'

Rose considered her divided feelings. She didn't like rats. However, they were living creatures and didn't deserve to be treated like "spanners".

A third party intervened.

'Good morning good morning!' enthused Eric, leaning around a corner of the dual cubicle. 'Are we all wakey-wakey?'

Before either of them could reply, he bustled into the shared sleeping area.

'Listen, I think Roj wants to keep both of you kept separate and under observation. I'm supposed to shepherd RoseRose and Arpad is watching the Doctor.'

He spoke in a cheery undertone, the kind of conversational gambit that meant any eavesdropper would be hard put to begin following the talk.

'It's just "Rose",' explained Rose. 'Singular.'

'Go forth and keep your eyes peeled,' warned the Doctor. 'Both of you. I'll be asking questions later.' He finished with a giant, mock-serious shrugging of his eyebrows.

Rose took her seat in the cab of a mission vehicle, one that looked vaguely military with it's gigantic caterpillar-type treads. Montag was driving, with a TEST rat sat next to him, while Eric and his sister sat on seats in the cargo bay, preventing the crated supplies from sliding around.

The further they drove from Serendipity, the more plant life became visible, ranging from giant sedges growing in clumps, to copses that gradually became woods and forests. Montag deliberately drove close to one of the smaller groups of trees, allowing Rose to see and exclaim at the "faterpillars" that infested the branches. They looked like thick dishes connected through the middle by a slightly thinner section, with a great irising mouth full of champing chitinous teeth in what must be the "head". Purple and black seemed to be the overall colour scheme, making Rose think bizarrely of blackcurrant and liquorice sweets come to life.

'Not so pretty, are they!' joked Montag. 'They puzzle the fnorp out of Mike, you know. They breed like mad and have so few predators they're going to eat all the food.'

The rat, with 3 dyed or tattooed into it's fur, bobbed and signalled "Good" and "eat" and "!"

'Do you eat them?' asked Rose directly, with unwilling fascination.

"Yes" agreed the rat, baring it's teeth.

'Wow – you don't often see them smile!' commented Hypatia. 'You're honoured!'

Smile? wondered Rose, before the penny dropped.

'Oh – I thought it was going to bite me!'

The rat indicated itself with one small paw.

"Good" it signalled again. "No" "Bite".

Montag offhandedly cuffed the creature.

'Don't be cheeky, you. No, Rose, they don't bite humans – their stomach lining dissolves if it comes into contact with human blood. On the other hand they are engineered to mimic human digestion.'

The young woman understood the reason for that – allow the rats to eat their way across an alien planet and see what food was edible, inedible or plain poisonous.

The Doctor is wrong, she debated internally. They are a lot more than spanners. Still creepy and over-sized, however.

They rattled along in silence for another ten minutes, scaring sillipedes away from the carcass of a freshly-killed "Big Bug" en route.

'Where are we off to?' she asked. 'I forgot to ask before.'

Montag pointed to the far distance.

'The first field we set up. Eric, d'you want to bore her with the details?'

Eric, frankly, didn't look at all bored at having to talk to a pretty young woman.

'Remember those Charcod areas you saw at sunset last night? Well, we're off on the daily run to each of them.'

"Charcods" turned out to be invented slang for Charge Couple Devices. Primitive, as she'd been told, but robust, reliable, easy to create from local materials and capable of being churned out in large numbers. The crated supplies were more CCD's, being ferried out to replace older ones damaged by the elements, roving wildlife or simply used to increase the size of the field.

The Doctor, had he been present, would have butted in at this point, explaining that using two widely separated fields – they were almost twenty five miles apart – gave the ability to use them for baseline interferometry. Without his presence, Montag explained that the two square acres of CCD's downloaded information to a central collection point, a data dump that they would upload onto a disk and take back to Serendipity. Once finished here, the process would be repeated at the other site.

When they approached the first Charcod field, Rose whistled in appreciation. It had been designed and laid out in a checkerboard pattern, arranged in squares that stood two yards per side; just sufficiently wide to allow the innermost CCD's to be reached and removed when needed. Each individual CCD stood on a brick-sized mounting allowing it to be pivoted slightly, and from the bricks data cables ran to a black box the size of a dustbin – the data dump.

The mission members inspected silvery disks for evidence of damage or abrasion, swapping any such device for a brand new one. TEST rat 3 ran around underneath the disks, looking for damage from below. Montag unsheathed a long, plug-like grey device from a holster on his belt, inserting it into the data dump and pressing buttons. Lights blinked, internal circuitry hummed and after a minute the plug popped back out.

All tasks completed after half an hour, they were back in the rapid rider and off to the second CCD field.

Solo, and wondering when his subconscious was going to yield up a revelation, the Doctor glanced angrily at Arpad, who gazed coolly back.

'So what's your story?' asked the Time Lord, attempting to assert some dominance. 'Moral or political? Completely out of your depth or merely floundering?'

'Guilty of speaking Hungarian,' replied the other man. 'Thus, political. As an agrarian advisor I swim in the shallow end of our mission's specialist mismatching.'

Crossing his legs, the Doctor pressed both palms together and held his fingers pressed to his lips. He knew that part of the bigger picture escaped him at present, and it annoyed him.

Still, losing his poise and being unpleasant to the Hungarian simply wasn't on.

Standing, which put Arpad at a height disadvantage, he looked over the maze of partitions that divided up the dorm area.

Snap! went his fingers, amazingly loud. Arpad jumped.

'Tell me, did you explore the walls of this bunker after excavating it?'

'Examine what? Their splendid finish? Their creator's lack of interior decorating skills?' mocked Arpad gently. He flinched when the tall stranger whipped around, face fiercely animated.

'Do you have a floor plan of the bunker before all your equipment got imported?'

A liquid, expressive shrug from Arpad.

'Perhaps. Beatrice will have it if we do.'

Beatrice, apparently, was a volunteer for the mission. Bored of life in European Littoral Zone Three (previously Holland), she volunteered to come along as one of the Humpers and Dumpers, unskilled labour who would construct buildings for the expedition. Thanks to the bunker's discovery, she didn't need to build the shoddy short-term accomodation. She had, by way of keeping busy, taken an architectural interest in the bunker.

Arpad checked his personal comm unit, didn't get a response from Beatrice, whistled a passing TESTer over and told it to find her and her floor plan.

Beatrice proudly displayed a major thin-film motile hologram of the bunker layout, retrieved from her bunk, painstakingly measured and pencilled-in on the laminate. The Doctor snatched it from her and spread it over the sheets on his borrowed camp bed, clucking in cogitation.

A nice clean rendering, he concluded. There were the walls of the bunker, with the ribs - jutting out shortly - and bays – far larger intrusions - and support struts all limned carefully in black, the tiny liftshaft let into a column, and the second level, rendered in isometric angling from four different directions. Inset to either side were smaller isometrics and floorplans of the two smaller bunkers.

Excellent. Just what he wanted.

'I got the idea from looking out over all the partitions you installed here to create a dormitory.'

'They weren't needed for the pre-fab accomodation,' explained Beatrice.

'No! Not my intent at all. I meant, it isn't possible to depict what this bunker looked like before you arrived and took it over, what with all the clutter around. Now, I have this diagram.'

One thing called out to the Doctor: thirty metres inwards from the entrance ramp, the right side of the bunker showed a shallow bay only two metres deep. The opposite wall of the bunker showed a bay eight metres deep.

Tapping with his finger, he looked up at Beatrice and Arpad, and also the TEST rat, who looked interested as well.

'Notice anything here?'

Beatrice looked hard.

'Bad pen mezzotint?'

Rolling his eyes, the Doctor tutted in exasperation.

'Ask yourself, why is this bay so shallow whereas the other bays, including the bay opposite, are so deep by contrast?'

Maddeningly, Arpad nodded in sympathetic fashion to his mission compatriot.

'Aliens, Doctor. They don't design to human standards.'

"!" signalled the rat, waving a paw at the diagram. Arpad kicked it with a casual neglect that caused the Doctor to frown slightly at the man. Only slightly, but with enough implied back-up to make Arpad clench most of his major muscle groups.

Beatrice traced the outline on the laminate.

'Is that significant? I mean, it's just solid rock.'

The TEST rat bobbed up and down with excitement, clearly disagreeing with it's human superior.

'Significant? I rather think so. Your unresourced colleague here seems to agree.'

The Doctor didn't wait for approval or breakfast, he strode off to the relevant minimal bay straightaway, followed by two humans and a rat.

Practical matters imposed themselves immediately: the rear wall of the bay in question consituted a huge shelved area containing countless thousands of categorised stores in their individual plastic storage boxes. Collectively, the whole constituted a mass weighing in excess of three metric tonnes and was quite beyond the ability of any single person to move.

Starting at the bay's far corner, the Doctor began to probe the wall behind the shelving with his sonic screwdriver, obtaining a dull low frequency drone at first. Once he moved horizontally across the chamber wall for a few metres the sound changed to an even lower buzz., before reverting to the original sound again. He repeated the procedure at knee-height, then at floor level, getting the same aural variation again. Finally he surrendered the sonic screwdriver to the TEST rat with instructions to repeat the sounding process at shelf levels higher than he could reach. Arpad reinforced these orders with a finger drawn across the throat, hastily conjuring up a false smile when he felt that frown bearing down upon him.

"Mission data debit 74" read Roj on his mission analysis monitor, and groaned a little, feeling self-pity seeping in around the edges.

The mission generated a gigantic amount of data, constantly coming in from Charcod fields, the roving Sun Gun, their single optical telescope, the two solar telescopes and ten individual remote scopes planted out in the wilderness. So far information transmitted back to Earth constituted 26 of the total available. Their Lowry coil had taken two months to assemble, orient and test, during which terabytes of data had piled up waiting for transmission. Nor could the coil transmit constantly; it drifted off-axis after a hundred minutes and needed re-orienting every night.

Then there was the other data: the geology team kept bringing back kilos of samples for micropare analysis or storage or comparison, and the biologists were always crowing about finding new arthropod species or variants of the Kink Bush or that solonaceum would germinate in the bubble tent used for growth – all that needed to be compiled and converted for transmission. Say another 15 data equivalent in comparison to the stellar information. If they didn't get the stuff coded and sent they'd be here long after the ninth month retreival date.

With all this on his mind, Roj didn't hear what Rogan said first time. He looked up from the monitor with a querulous hmm?

'I said, that Doctor fella has got people moving the stores and shelving in Bay One. Claims he's found a big secret there.'

Predictably, the Doctor didn't react at all as expected when faced by a furious Roj, whose honest apoplexy at the sight of the disordered, dismantled shelving and carelessly discarded storage units was fearful to behold.

'Glad you could make it!' beamed the Doctor, ignoring the stream of shouted insults. 'Jusssst in time - to open the secret chamber!' he finished, with a dramatic wave of the arm.

He tapped the wall with one hand, whilst drawing the sonic screwdriver across the featureless grey rock, detecting where the tone changed and making chalk marks. Eventually he had a square nine yards high and nine yards across scrawled on the wall.

'I suspect that whatever's behind there has leached into the wall, which is why your TESTer agreed with me – it detected the scent.'

A nod and a wink at the rat, and it bobbed up and down with excited approval.

'What's that device you've got there? A geosensor?' asked Roj, having calmed down and now experiencing curiosity.

'Sonic screwdriver,' answered the Doctor. 'I take it you have seismic equipment for geology?'

'Yes,' slowly answered Rogan. He'd accompanied Roj to witness the confrontation at first hand. 'What, you want us to sound the wall? It's solid rock!'

Nevertheless he co-opted Beatrice to collect the bulky geophones and bring them back. Normally they were used vertically against the ground, and keeping them levelled horizontally took three people. Rogan powered up the portable remote monitor and whistled in surprise when the picture came up.

'Look at this!' he exclaimed as more audience arrived.

"This" was a narrow wall of rock, no more than six inches thick, behind which lay a chamber nine yards deep.

'Bingo!' grinned the Doctor, saluting Roj with the sonic screwdriver. 'Also, told you so.' He turned to Rogan. 'What have you got that will cut rock?'

Rogan considered for a moment.

'UHB Cord, though it might take two tries.'

'Uh-uh,' disagreed the Doctor. 'Too destructive. Molecular valency stripper?'

Rogan looked blank.

'Cold fusion torch?'

Rogan looked perturbed.

'Xylene cutting flue?'

'Ah – we've got a sacrificial superwelder.'

'Super!' enthused the Doctor. 'I'll mark out a cutting area, say two yards by two.'

'Well, if you say so. It'll only cut an inch into rock like that, you know.'

'Then it'll take six passes with the welder, won't it?' interrupted Roj. He felt like asserting himself as the mission leader again, unaware that the Doctor was quite happy for him to do so.

Gouts of unbelievably foul fumes sprang from the rock wall when the cutter was applied, driving most spectators away and back to their work. Only the Doctor remained, using a quick-drying resin glue he'd discovered in a storage box to adhere a big metal bolt to the wall. Whilst Rogan, clad in a protective ceramic-weave suit and mask, scoured the chalk-marked line ever deeper, the Doctor looked for and found a long coil of cable. He deftly danced around Rogan, threaded the cable into the bolt and threw a hitch into it, unrolling it across the bunker floor. Backing away, he bumped into Roj, who carried a large, utilitarian case with an unpleasantly military look to it. Whilst the Time Lord looked on in some trepidation, Roj used a palm-lock to open the case and remove a functional, matte-finish weapon.

'Plasma bolide carbine,' mused the Doctor aloud.

'Dead right,' added Roj. 'We were issued this single weapon in case of large hostile fauna. So far it's sat under my bed, but I'm not taking chances with that chamber. It could be brim-ful of sillipedes.'

The Doctor eyed the weapon warily.

'Bit of overkill, ain't it? You could stop a charging elephant with that.'

'A what?' asked Roj.

'A ten ton truck.'

A sudden silence assaulted their ears, unusual after the high-pitched whine of the superwelder.

'If you can help here - ' began Rogan. The two others helped him to move the cutting equipment a safe distance from the rock wall, and Roj understood the reason for the cable: Rogan hadn't quite cut through the rock wall, since that would have sent a stream of molten rock and welding rod into the chamber.

'Heave-ho!' called the Doctor, taking up the cable and pulling. The other men joined him, and others came to help, knotted-handed, with the tug-of-war, until the wall rended with a series of sharp cracks and collapsed outwards, falling flat on the bunker floor, breaking into a jigsaw of broken blocks with a collosal bang.

'Holy mother!' exclaimed Rogan, peering into the chamber.

'Oh! Oh, fnorp,' added Roj.

'Aha!'

The last word came from the Doctor, who didn't seem bothered at all.

FIVE

No sooner had Rose and her mission members stopped and debussed from the Rapid Rider to service the Charcod acreage than an urgent, penetrating squawk from the vehicle's control fascia recalled Montag.

'Get back in here!' he yelled to them, starting the engine. 'Emergency!'

He knew no more than that, despite all the questions they asked.

'Prentiss called. Said the Doctor's uncovered something big and important and dangerous, but he didn't have details.'

Ignoring any more questions, he erected the cab and kicked the TEST rat into the rear cargo compartment.

Eric looked slyly at Rose.

'He seems pretty good at getting into trouble, this Doctor of yours.'

Rose sighed ruefully.

'Yeah! Yeah, you bet. If there's trouble around, he'll find it.'

She chirped sympathetically at the rat, which lay, resignedly, on the cargo bay floor.

By the time they returned to Serendipity base the panic was over and cold determined action was underway. Teams of people were moving dismantled shelving and stores from Bay One to Bay Eleven opposite, whilst lighting was brought up to shine into a newly-exposed cavity in the bunker wall. Staff with cameras and filming equipment stood back from the hubbub at Bay One, where other gofers were dragging weighty pieces of rubble away from the new discovery.

'Hi there!' beamed the Doctor at Rose as she dodged between other people. 'Front row seat? Sorry, no popcorn.'

Rose looked at the hidden chamber so rudely exposed, and gasped at what she saw.

Not so much the corroded, oxidised, collapsing equipment within as much as the three huge aliens also there, sat in dead floppy postures at their imploded consoles.

'They must be three metres tall!' she breathed, causing passing staff to quiver with worry.

'Yards, not metres,' cautioned the Doctor. 'Imperial only. However, I agree. Not quite nine feet tall.'

One of the scaley bodies sagged abruptly to one side, creating a dust-slide and a nervous twitch from Roj, whom Rose saw cradling a ferocious-looking sidearm.

'Be careful!' warned her mentor, speaking to Roj. 'That's not life, that's reaction to airflow and thermal differentials.'

Rose stared at the starkly-lit chamber, taking it all in with the sharp eyes of youth, even if she didn't fully understand the implications of what she saw.

What she saw: a giant stone cube nine metres to a side, where three sets of island consoles had been placed in the middle of the floorspace. At each console sat the corpse of a giant reptilian alien, great curving beaks flaring under empty, dusty eye sockets, wearing dulled silvery armour.

Mike directed stretcher-bearers to the nearest alien, and then had them gingerly lever it from the absurdly spindly stool it sat upon, and onto a stretcher. Despite the care they took, brittle snapping sounds told of ancient joints being fractured, and layers of epitheleal debris cascaded from the body.

'Biology,' ordered Mike, before turning to the other two aliens. Roj and Rogan were right alongside him.

'Look at that,' indicated the mission leader, pointing to a dessicated hole in the side of one alien's head, a hole that gave a view of an empty brain-pan. 'I could fit my fist in there.'

One of the other staff discovered the cause of said hole-in-head: a weapon dangling from the triple talons of an alien. Using extreme care and lazy-tong grips, the weapon was dislodged into a plastic specimen tray, clattering into it with a collection of rusty metal flakes. The second remaining corpse had a weapon, too, one that had fallen to the floor. In fact the console where the absent alien had sat displayed a weapon, too.

Rose peered into the specimen tray as it got passed out of the chamber.

'Weird looking gun,' she murmured.

'Made for a creature with three digits,' commented the Doctor. 'Mutually-opposable around a common axis, meaning a triple thumb, in effect. Interesting. Not seen that before.'

Other staff were poking around inside the newly-discovered chamber.

'This stuff's junk,' opined one. She picked up a monitor to prove her point, and the item disintegrated into friable rubbish, metals, plastics and a weeping thin-screen display.

'Eight hundred years of decay,' commented Rogan. The two remaining alien bodies were removed.

'They all shot themselves,' observed another member. 'All of them, in the head.'

'So would you if you got locked into a rock tomb nine yards per side,' said another.

A semi-professional autopsy took place in Biology, under the tutelage of Mike. The huge alien body was cut apart with power-saws and medical gauntlets, resting on two trestle tables placed end-to-end, after being scanned with a portable X-ray wand. A scavenging microphone caught the Mongolian's words.

'Mummified,' explained the biologist, poking the squamous skin. 'Over eight centuries has left little but the skeleton and the epidermis. Not a species humanity has ever encountered before, either.'

Before an attentive audience, he gestured at the cranium, long emptied of matter and also sporting a giant hole at the temple.

'From the trauma signature, I understand the damage was done by a directed-energy weapon fired at point-blank range. Probable impact rated in megawatts.'

Now, he gestured to indicate the whole creature.

'At just over nine feet tall, this creature corresponds precisely with the dimensions of those that constructed this bunker. How unfortunate that he and his colleagues were trapped in their chamber.'

Beginning at the thorax, Mike began to slice open the parchment skin and scales.

Rose, one of the attentive audience, felt her skin crawl at the idea of being trapped in an underground cave with no exit. No exit, no water, no food.

The Doctor, another of the attentive audience, shook his head at the prejudice and incomprehension being displayed. No idea, no curiosity, no answers.

'I applaud your ability to uncover the unexpected, Doctor,' flattered Roj. 'We're currently doing a sonometric and geoplasty survey of the whole bunker, just in case.'

Flattery did not distract the Time Lord. Not at all. His eyes bored into Roj, who felt uncomfortable enough to continue where he hadn't really intended to. Despite being protected by the bulk of his table, he felt rather naked under the inspection of the man opposite.

'So we've found some of your alien predecessors. Perhaps they sent out that SOS you mentioned!'

An amused, mocking sneer crossed the Doctor's face.

'Hardly! I've already found the source of the emergency message. Those aliens weren't "trapped" in that chamber, either, matey – they were placed there deliberately.'

Roj felt his newly-acquired assurance fading away, as it tended to when faced with this Doctor character. Of course the aliens were trapped in their ghastly little dungeon, why else would they be there? And as for that SOS –

'Wait a second – you know where the message is coming from? This splendidly mysterious message that brought you here in the first place?'

With a shrug, the Doctor explained further.

'Yep. Comes from one of the moons in orbit around ZLM Prime.'

With that reply, Roj found his confidence returning.

'As if! All this world's satellites are barren rocks. No atmosphere, none of them. Tidally-locked rocks.'

The Doctor sighed. This expedition had to be the worst-equipped, in terms of mental outlook, that he'd ever come across. The Serendipity bunker seemed to be a manifestation of their weltanschaung, sticking collective heads in the sand and ignoring what they didn't like.

Abandoning Roj, he trotted over to see what the technicians had salvaged from the hidden chamber, finds laid out in specimen trays or non-reactive sheets of plastic. Uppermost in his mind were the three weapons – which turned out to be corroded into uselessness, eaten away from the inside by decayed energy cells. Very little else was more than junk, liable to fall apart under the gentlest of scrutinies.

'Memory unit?' guessed a shaven-headed tech new to the Doctor, holding up a sturdy boxlike device, girded with tarnished copper banding. Small holes dotted each face, with a few occupied by tiny dartlike crystals.

'Possibly, possibly,' he replied. 'Get those crystals into a suspension of buffered Miller's solution before they oxidise or photophage.'

Using tweezers, the technicians hastily plucked crystals from the unit and dropped them into a sterile jar filled with the semi-opaque solution.

'Nice try,' muttered one of the staff, turning the multi-holed housing to show the underside: a gaping rusty hole.

'Oh well! Nothing ventured!' cheerily replied the Doctor. The shaven-headed tech frowned in annoyance at the guileless response.

Watching the gradual dissection of the giant alien, Rose felt glad that it was so long dead. Nothing fresh about it, meaning that the dissection became more like a dissembling. Mike carefully peeled back scaled skin, revealing massive bones and stringy threads of dried proteins, working from the flensed skull down to the huge taloned feet and incongruously delicate triple-fingered hands.

'Humanoid, in essence,' he decided. 'Two arms, two legs, single head, binocular vision, upright posture. Evidentially, a creature that evolved from a predatory species.'

With the autopsy complete, Rose accompanied the audience back to the salvage tables, where alien's armoured clothing lay on a table.

Sad, she thought. All that's left of them is a handful of jumble, three mummies and their clothing. Clothing that looks, kind of – military. Or a police uniform.

Fussing and mumbling under his breath, the Doctor came to stand alongside her.

'Not finding the locals helpful?' she teased. 'They should be, you just discovered a secret chamber for them.' She indicated the sad display of clothing. 'Complete with their old uniforms. Like a museum'

'Free of charge, too,' he added, gloomily. 'Another part of the puzzle. Which I haven't managed to solve, nowhere near.'

Linking her arm with his, she tugged him off to the canteen area, which buzzed with staff gossiping and speculating and drinking cocoa. Steepling his hands over his mouth, the Doctor reclined his lanky frame and sat silently. Recognising a meditative withdrawal, Rose avoided any overt questions about whether things here seemed as dangerous as her companion considered.

Very well, what were the aliens doing here? began the Doctor, having one of his two-sided conversations where he played devil's advocate and angelic counsel simultaneously.

Exploring. Obviously, exploring.

No, they weren't here to explore. This base took months to carve out of a rock formation and after construction they simply sat in it. There were no other bases of a similar size, no traces of expeditions or explorations anywhere else on ZLM Prime's surface.

Very well, they were here to carry out research into the peculiar behaviour of a non-Cepheid non-radial pulsator star with unique periodicity.

More viable as a supposition. So. A solar research expedition. Why such a huge bunker?

Huge aliens, huge artefacts.

Why hide three of their members in a solid cell?

Punishment. The equivalent of imprisonment, for unimaginable alien transgressions. Huge transgressions.

Hardly! The air in that cell would have been exhausted in – several criteria need approximating but best guess – ninety minutes. Fusor technology wasn't capable of creating a solid wall quickly. Twenty minutes of construction to punish three crew for ninety minutes?

Twenty minutes construction time rules out the possibility that they were accidentally trapped.

Certainly. The heat and fumes from fusor operation would wake anyone not already dead.

Or – perhaps – not a tender thought – that wall wasn't to keep them in. It was to keep factors undefined out.

Ah! Paradigm shift! Excellent rationale. Makes more sense. Put your threesome in an unbreachable protective space.

Then by definition we have an external threat. One so severe that it requires desperate measures, abandoning three crew.

No – not abandoning: sacrificing! Sacrificing three members, so that a greater number could escape.

Our external threat explains why a shuttle craft went into orbit on emergency maximum fusion boost. They were making an escape whilst their trio of volunteers decoyed the threat.

Volunteers maybe. They all committed suicide. Volunteers - maybe.

Perhaps their decoying wasn't totally successful, then.

It succeeded. Recall the broadcast coming from that moon. Their shuttle is up there.

Note that they didn't even try to burn a way out of their cell. No scorch marks or cauterisations. The threat may have persisted in the bunker outside their cell.

None of this identifies what this "threat" may be.

Yes. "May be", correct tense, rather than "was".

'Well, I've worked out what our trio of mummies were up to,' announced the Doctor, stretching a kink out of his leg.

Half a dozen faces turned to look at him.

'Do tell,' asked the sour-faced shaven-headed tech.

His only answer was a cautionary finger-wag from the Doctor.

'Certainly not! I've made myself very unpopular with Roj and Mike by asserting wild, fantastic theories that invariably turn out to be correct. I want a bit more proof than my ineluctable logic.'

The tech frowned even more, a look that seemed to come naturally to him.

'Inel-what?' he sneered. 'I'm fourth in charge after Chadwick, and he's always off digging. So watch your plabby lip.'

'Love you too,' mocked the Doctor, getting to his feet in a whirl of coat. Arpad, recollecting that he needed to keep an eye on the stranger, left a cup of cocoa and followed. Rose began to shove her chair backwards, only for TEST rat 3 to appear and squeak at her.

"Come" it signalled. It turned to go before seeming to change it's mind and turned back. "Please" it added.

She sighed. Back to the Charcod fields, it seemed. The rat indeed scuttled out of the bunker, back to the Rapid Rider. Eric and Hypatia waved to her, Montag already revving the engine.

'Sorry I'm late, appointment with a cup of cocoa,' she apologised. Montag rolled his eyes. 'Can I ask a question?' she carried on, attempting to avoid the subject of being late.

'Ask a question! Rose, you never stop talking!'

Eric burst into laughter, only to receive a venemous glare from Rose.

'What does the "T.E.S.T." part of your rat's name come from?'

Rumbling out of the base perimeter, and able to pay her more attention, Montag shook his head again.

' "Talks English, Scientifically Trained". Bit of a misnomer, everyone on Earth speaks English. Also, out here, a bit of a pun – "TESTer" because they test what's safe to eat or drink.'

'Ohhh, right,' nodded Rose. She was used to the TARDIS exerting it's usual language translation magic when visiting planets in the Zorg Nebula or whatever. Speaking English seemed a bit – well, dull.

The Doctor came across Mike busy taking photographs of the dissected alien corpse, from different angles and distances, with a metal ruler alongside for scale. The microbiologist looked up briefly at his new visitor; the rest of his audience had left long ago. Arpad hovered silently behind the Time Lord, watching and listening carefully.

'I've suggested to Roj that we inter the other two alien bodies. I'm not really happy at dragging the remains of more intelligent creatures across the galaxy for the delectation of the Grey Emp – er, The Administration.'

Grinning at this tell-tale slip, the Doctor cocked an inquisitive eye at the remains.

'Not seen a species like this before myself. You say you haven't either?'

Mike shook his head and took another photo. Intelligent, space-faring races were not common. He knew of the predecessor varieties: Daleks, the Cybermen, Rutans, the Sontarans, the Draconians, all of whom had established stellar presences across the galactic arm. This reptilian alien was utterly unfamiliar.

Musing, the Doctor looked over the dissected body. A novel species to him, too. Never encountered in his almost eight hundred years of intergalactic travelling. They had interstellar travel technology, and were at least the technological equivalent of humanity, so they ought to have spread across enough of the galaxy to have been discovered before now.

Yet they hadn't.

Perhaps they weren't around to be discovered any longer. Another lost race, remembered only by their crumbling cities, derelict spacecraft and long-forgotten outposts.

Finally, Mike stopped taking pictures.

'That's enough. Thijs and Lev can process and collate the magazine.' Standing back from the body, he looked hard at the Doctor.

'Care for a cocoa? I've had enough of trying to make sense of a discipline that's not mine.'

'You looked competent enough.'

Mike snorted.

'Do you know why they call me "Mike"? Because Cholon Khongordzolny is too hard. Mike, for Microbiologist. Not a pathologist.'

Trailing the muttering and grumbling scientist, the Doctor was led back to the canteen area, where he declined yet another cocoa.

'Already had three,' he lied. In fact he wanted to listen to Mike grumble, sure and certain that there were facts and associations waiting to emerge from the biologist when he finally stopped indulging in sub-audible complaining. The Time Lord couldn't yet explain or analyse completely why he felt that the situation on ZLM Prime was so potentially hostile, only that he did. Producing his subconscious as reason and rationale wouldn't convince anyone; he needed facts. Hence the hanging around with Mike; sullen, grumpy Mongolian microbiologist Mike.

The microbiologist stirred mock-choc powder into his cocoa with savage concentration, muttering.

'Pardon?' asked the Doctor, judging the moment to be correct.

'This planet!' complained the other man. 'Plabby place! Baffles the fnorp out of everyone.'

'You're the expert. I'm only a visitor.'

Mike – or Cholon, if you bothered with aboriginal names, kept on.

'Do you know, there aren't enough predators in the ecosystems here.'

Wordlessly, the Doctor primed both eyebrows in an "oh really?" expression. Mike carried on, happy to have a non-judgemental ear sit and pay attention to his long-treasured ramblings.

For one thing, there genuinely were far too few predators. The local equivalent of arthropod herbivores known as "Faterpillars" and "Big Bugs" happened to be eating all the plant life at an alarming rate without being culled back by predation, in what might be termed an anti-Malthusian envelope. Many of the plant and animal life-forms were failed genus possessed of dormant genes that didn't appear to have any proper function. Irrelevant sidelines in the evolution lottery, mayhaps. Since they didn't have anyone with the proper genetic analysis skills and training that could relate the flora and fauna to their environment, the Biology staff had to make educated guesses. Of course, since the mission's whole ethos was heliographical, biology took a distant second place and there was no great emphasis on properly analysing the local life-forms down to the DNA level.

Holistically, the ecosystems were wildly skewed. The Weepy Willow trees lacked sufficient nutrition to grow properly, remaining etiolated for life. The Kink Bush's seed pods never matured, no matter how old the bush, yet the bushes were everywhere. The Kackti were useless at deterring browsing arthropods, since their spines fell out at the slightest knock, rendering them defenceless.

The entire ecosystem was a nightmare, convoluted, contradictory, redundant and inexplicable.

'I only imagine that ZLM kills off the majority of life on the planet's surface when it flares up. After that what's left struggles out of the wreckage and continues.'

A logical and reasonable assumption. A twist in his memory warned the Doctor that the explanation felt too easy, too simple.

Mike hadn't finished his expressed worries. Another cocked eyebrow from his listener brought forth more information about aquatic ZLM Prime ecosystems. The mission knew nothing about them. Not only were there no marine biologists, they didn't even possess a boat. Sun Gun One could travel over relatively smooth water at a pinch, if it had to, but Roj had forbidden that unless unavoidable; the hull's hover-skirt would lose its air cushion easily on moving water. There might very well be an enormous amount of marine life in the shallow littorals, or nothing at all.

'Listen, can you be increasingly careful about the research you conduct?' asked the Doctor, hoping not to be required to give an explanation.

'Why?' asked Mike, genuinely surprised.

'No specific reason, nothing I can point to and say "this – this, is a problem". Those aliens were deliberately interred for a very calculating reason, however.'

With a snort of mild derision, the other man shook his head.

'Aliens! Who knows how they think!'

This time it was the Doctor who snorted with mild derision.

' "Aliens" does not make them "Morons"!' he chided.

Of course, from a human perspective, the Time Lord constituted an alien with different modes of intellectual operation. To him, humans were aliens, even if he managed to second-guess how they would think in most circumstances.

'Mike, I've been around a large part of this galaxy without ever coming across aliens like these before. My suspicion is that they're now extinct. What happened on ZLM Prime might have a bearing on that.'

'How?' asked Mike. Personally, he felt that this odd stranger was way off the mark here. On the other hand, he'd found that hidden chamber when the entire expedition had missed it for the past seven months.

'They were here conducting research. Doubtless into ZLM itself, with the odd foray onto ZLM Prime's surface.'

Behind him Arpad, hitherto silent, stifled a snigger that caused the Doctor to roll his eyes in exasperation and turn to the shadow.

'Really! You sound like a cheesy scientist making the final line in a cheap film. "They meddled with things mankind was not meant to know!".'

'So glad I entertained you.' He turned back to Mike. 'I'm serious. Nobody here has the big picture of how ZLM Prime operates and until you do there ought to be a more cautious attitude. Looking before leaping.'

Mike flexed his fingers, considering. Being the expedition's second-in-command, he could certainly slow research into anything biological, and even recommend an overall emphasis on caution to Roj.

Who might very well ignore the advice. Still, he'd see.

'Go on, then, Doctor. I'll adopt a more, shall we say, reflective approach.'

A beginning, the Time Lord thought, leaving Mike to sip cocoa. Arpad toddled along in his wake, trying to keep up and having trouble. Short legs.

'Seriously, Doctor, what can possibly harm the entire expedition?' he called, trying to slow his charge. 'Roj has that cannon of his. Mike didn't mention it, but he got issued with an induction pistol for smaller dangerous animals.'

'Let me guess – unused to date?'

'Oh, no, it got used plenty when we cleaned this bunker out. Mike's a crack shot, he got rid of dozens of sillipedes. Pow pow pow, one after another. Had to be careful with the ones crawling overhead,' and the small Hungarian mimicked a man with a pistol, picking off giant carnivorous insects.

Yes, pondered the Doctor, which created another puzzle. One man with a simple slug-chucker stopped hordes of vicious giant centipedes. So what did our alien friends have to fear, with their formidable hand-held energy weapons? Fear so badly that they were sealed inside a rock tomb with hours to live.

'There's nothing for it,' he grimaced. 'I'm going to have to get up to that moon and locate the alien's shuttle - '

'Trinarian,' interrupted Arpad, rolling the "r"s with Magyar relish. 'I just invented it. After their triple-digit hands.'

Despite himself the Doctor laughed. Humans! How could you not admire them!

'Okay, the "Trinarian" shuttle. I know that it's power systems are still operating because of their distress signal. If I can locate it then we might get a bit more information on what they were doing here, and why they left so hurriedly.'

'Oh – could it have been the sun?' enquired Arpad. 'You know. Flaring up.'

I hope not, worried the Doctor. His temporally-sensitive hypothalamus was picking up a fluctuation in local space-time. ZLM was about to flare up.

SIX

By the time Rose got back to Serendipity, the Doctor had disappeared and Arpad was telling a wild tale about the fission-boosted take-off that the TARDIS had, getting into orbit too quickly for the human eye to follow –

'Yeah, right,' nodded the young woman, keeping up the fraud of being a rebel colonist with a pocket-spaceship. 'Where's he gone?'

Arpad pursed his lips and scowled, taking a slip of paper from a pocket to read his written prompt.

'He said to tell you that "the space-time continuum is jiggered and well dodgy to mooch about in, and he didn't want to compact disk your bread knife". Is that code?'

Rose gave a reflex, lopsided smile.

'Yeah! Yeah, code. Something like that.' "Compact disk" – risk. "Bread knife" – life.

Not noticing the teary glint in the young woman's eye, Arpad rattled on.

'He wanted to track down the alien's escape ship. Which, according to what Amir told me, he located on one of ZLM's satellite moons.'

A pre-tertiary temporal whorl sent the TARDIS, and the Doctor, reeling.

'Hold on!' he called out, not merely for himself. If the TARDIS got encouragement she'd be all the better for it.

He dragged himself around the control console, punching at the relevant buttons while he still could.

'This was a mistake, Doctor,' he sternly warned himself. Local time-space distortion had already begun before he'd even departed from ZLM Prime, as evidenced by his limbic warnings. The symptoms were unknown to Homo Sapiens, so Arpad had been totally unaware of the potential hazards of throwing a temporal traveller into the vortex.

As a Time Lord, the Doctor had been very tangibly aware that navigating to the target moon would be difficult. "Difficult" and "Dangerous" were two different states, however, and he'd veered into the latter already. ZLM's temporo-spatial energy dump into local space-time amounted to terawatts of energy already, even before the star's fluctuations were visible with the naked eye, and meant that the Gallifreyan time-travel vehicle was vulnerable to displacement.

After almost an hour's travel in four-dimensional space-time, the Doctor judged that he was still only half way to his target landfall, and he'd been thrown around the control room for most of that hour. To get closer meant suffering more contusions as the TARDIS tried to maintain a regular course in the endlessly multiplying four-dimensional shadows of the time-travel medium. With difficulty, the Doctor realised that the tempobaric ripples generated by ZLM came at multiples of nintey seconds, and adjusted his shuffling around the control column accordingly.

Finally, judging that the problems of landing accurately on a small rocky satellite would be impossibly difficult whilst using temporal transfer, he dropped the TARDIS out of four-dimensional spacetime and into the conventional universe, emerging only forty kilometres above the dead moon; unpleasantly close enough for a warning klaxon to start hooting enthusiastically.

'Quiet! A genius can't hear himself think!' he catcalled, frantically reading off the local gravity, magnetosphere and solar wind data.

Five minutes later he had the TARDIS sweeping over the barren, shattered bleakness below, until a familiar alien bleeping began to emerge from the speaker systems.

'Not quite the Chemical Brothers, but it'll do,' he muttered, slowing his descent and beginning to cast the sensor arrays in a rapid spiral pattern. 'Aha! Gotcha!' he burbled, happy at last.

Ancient regolith, undisturbed for centuries by any artificial means, stirred and displaced under the impact of a descending space vehicle, a peculiarly shaped and coloured one more reminiscent of a twentieth century judiciary artefact. Situated on the hemisphere facing away from ZLM Prime , the landing site still baked under the cauterising blast of radiation from ZLM itself, and would do so until the moon swung away into shadow again in eighteen hours. Gradually and reluctantly, the dust settled and that same familiar silence reigned on the un-named moon of ZLM Prime.

Or at least it did until a figure wearing an ungainly spacesuit emerged from that same strange spaceship, lurching and wobbling unsteadily across the ground. The figure wore a bright white bulbous suit, an equally bulbous helmet with a gold-tinted visor and a great white backpack. Clearly unused to the protective garb, whoever wore it managed to lurch and bounce across the cratered rock landscape with speed if not style. Low-gravity leaps were easy to begin but hard to manage and tended to end in unpleasantly hard landings.

'Ooof!' exhaled the Doctor, involuntarily. His last practice with an enclosed environment suit had been during the long descent into what he'd subsequently nicknamed "Nick's Coal Hole", and that suit had been far better designed than the Aries Lunar Colony suit he currently wore.

'So much for cheapness!' he ruefully commented. Any further self-criticism along the lines of cheapness or impact on fallen arches died on his lips as he topped a small ridge of smashed rocks and witnessed the source of the alien broadcast.

There it lay. A long, crumpled, bright silver tube with collapsed venturis and battered canard foreplanes, dug into the moon's surface at the end of a trench scraped out by main force. Remarkably, young Friday had guesstimated the shuttle dimensions more accurately than the Doctor, as he noted in passing whilst approaching.

More remarkable still, when the Doctor got closer, was the hectare of ground covered by graves. Painstakingly excavated, with a vertical pillar of basalt serving as memorial cross for each interment, inscribed with a cursive alien script. The graves formed a giant radial pattern of sixty seven in total. They had been cut with extreme precision, without any spoil being removed, and with edging of millimetric tolerance – clearly fusor technology at work.

So, by virtue of Occam's Razor, these graves were the last resting places of the aliens who had been present on ZLM Prime and who abandoned that planet in the face of – what?

'Let's see what hospitality you have to offer,' he muttered, stalking up to the side of what appeared to be a very large atmosphere-capable shuttlecraft. Pitting and scoring marks onn the hull exterior spoke of a very long wait.

The first problem was actually reacing the hull door. Thoughtfully, the aliens had constructed a flight of rock steps up to the entrance, but the external control panel stood eight feet above the last riser, well beyond the Doctor's reach. He was forced to try an undignified low-gravity leap, punching at buttons at the apogee of his leap until the door slowly grated open.

Stumbling over the sill, the bulbous-suited explorer floundered inside until securing his boots on the floor thanks to their magnetic underlay. His suit headlight shone bravely down a corridor constituted of complete darkness.

Everything constituted an architecture and environment bigger then he'd ever been used to. The Draconians possessed a reptilian culture at a much smaller scale – yet with the same militaristic lines: no decoration, stark functional lettering and an air of authority. Turning to look down the main axial corridor, the Doctor saw buckled panelling and split weld seams, more evidence of a bad landing. There was no atmosphere in the corridor, either. He checked the suit's radiation monitor, grateful to see it hovering only slightly above background. If the ship's fusion bottle had collapsed then there'd merely be a giant glass crater here in lieu of a ship.

Picking a room at random, the door slowly grated open to reveal a bare chamber, empty of anything. The next one he tried was bare also, but the third contained racks of weaponry, designs similar to those discovered in the Serendipity bunker. Higher shelving carried larger, double-barrelled versions, and there were hints of other weapons not properly revealed in the headlight's glow. All their readouts were dark.

'Sell-by-date long gone, eh?' he joked with himself.

The axial corridor led to a pair of massive interlocking doors that patently refused to budge. With a bit of poking around, the Doctor uncovered a manual access point, crank socket and crank handle. It took him minutes of intensive effort to grind the doors open, his suit's inner-lining soaking up sweat, until a bright slice of light escaped from the control structure and into the darkened corridor.

Once he stepped into the giant control bubble he understood why the door remained so stubbornly shut – a hole as big as a football loomed in the curving crystal viewport that took up a full third of the bubble. Five dessicated alien – "Trinarian" – bodies lay on the floor, the last one nearly at his feet, arms stretched out in a despairing posture.

Overcome by sadness at the waste, the Doctor sat on a low console support. He could read the situation like a book: a desperate crew running short of drive fuel attempt to land, damage their ship irreperably and bury their passengers. Who died in rapid succession from lack of air, water and food. Then, in a final bitter irony, a meteor destroys their last remaining sanctuary, asphyxiating all five survivors before they made it to the door.

Despite the crew's death, the control bubble's circuitry continued to function, mostly unimpaired. One bright blue light in particular caught the traveller's eye: positioned above a big yellow button, the light flickered on and off in a seven second rhythm. Pressing the button again caused the light to blink out, ending a useless message that never helped the survivors.

'Requisat in pacem,' muttered the first visitor to that desolate spot in over eight centuries. He carefully walked back to the door, then noticed that the alien nearest the doors wasn't simply lying there in a supplicant's pose – a glint of metal showed between the wasted hands.

Vacuum dessication had rendered those hands as taut and constrictive as iron bands, and the Doctor eventually rolled the whole body onto it's side to lift it clear of the artefact.

'Well well well! My trip may have been worthwhile after all,' he murmured.

Scowling internally, Rose savaged her soya-steak sandwich on toasted bread. Night had already fallen, different shifts of staff were sitting down to eat, yet the Doctor still hadn't returned. Surely a short trip to one of those moons now rising above the horizon shouldn't take so long?

Not that she could do anything useful. Moping around uselessly would annoy the Doctor, if he knew what she was doing or failing to do. Eric and Hypatia had abandoned her to the scrutiny of Christy, Roj's wife, who treated her as a cross between a succubus and an anarchist.

Faintly, if unmistakably, a subsonic quiver ran across the bunker and rattled loose crockery.

'Messages for Earth?' asked the young woman. 'That was the Lowry coil transmitting.'

Christy blinked a little in surprise, her lined face changing from wary to wondering.

'Operating, not transmitting. No, no messages. Kendal has to re-orient it for hours each night. We've gotten used to it's noise, I quite ignored it.'

Rose pursed her mouth in appreciation of Kendal's diligence, only to be disabused by Christy.

'If it keeps the horrid little ignoramus out of our hair for hours at a time I'm quite happy.' She stirred her coffee clockwise with extreme vigour, muttering more bile beneath her breath.

'Is he the one with a mouth like a cat's bum?' asked Rose, greatly daring. 'Bald - looks like a gherkin.'

Christy nearly coughed on her drink with mingled amusement and surprise.

'Don't make me choke! Yes, looks like a pickle and with the same temperament: sour. As for a cat's fundament, I can't possibly comment. We don't have the income to afford one.'

Whoops! realised Rose. Another twenty-first century slip. Cats were expensive, so presumably rare, and they'd clash with all these giant rats everywhere.

'Mickey's – my sort of fella – his nan used to have a cat,' she carried on, trying to thaw Christy even the slightest bit. 'Big fat spoiled thing. She fed it bacon and chicken breast and pate on toast.'

Christy considered this to be boasting of the worst kind. Able to afford a cat licence, and a cat, and bacon and chicken! Sheer snobbishness! Once again she stirred her coffee, anticlockwise this time, with equal ferocity.

Having finally bounced to an inelegant stop in front of the TARDIS, the Doctor entered appreciatively.

'Gravity! And air!' he exclaimed in relief after unclamping, unsealing and removing the big, awkward ALC helmet. The rest of the suit, resembling a slightly-flexible suit of armour, came off progressively in pieces as he used the remote standing "tailor" to unlock and unseal the Life-Support Pack. The last item removed was a glitter-scrunchie used to keep his hair well back and out of his eyes whilst he wore the helmet.

'Bit too kitsch, that. Must have Rose get me a more masculine one.'

Flexing his fingers, he took a deep breath and checked the four-dimensional map of local space-time, represented on a hologram projector.

Not good. His long EVA trip to the Trinarian ship, exploring there and returning had swallowed up two hours. ZLM's flare-up was even now beginning to trip sensors in three-dimensional space, and had further distorted four-dimensional space-time. The energy cycle had spawned temporal eddies in the vicinity of ZLM Prime and the other un-named planets closer to the sun, where gravity impinged on the universe's underlying fabric, and those perturbations had intermingled with each other and following distortions from ZLM.

Clad once again in his image-affirming camelhair coat, the Doctor huffed quietly and shook his head. Navigating a four-dimensional maelstrom like this to land back on ZLM Prime – it just wasn't on. He'd have to resort to simple three-dimensional transit in the conventional universe, using nothing more complicated than calculus and trigonometry.

- and a little bit of cheating once he lofted the TARDIS from the barren rockery in orbit, managing to hurl his vehicle across nearly half the distance to ZLM Prime without mishap. Common-sense then trumped derring-do, and he piloted the TARDIS to a conventional landing close to Serendipity base.

'Relatively close,' he muttered to himself, starting a multi-kilometre trek from the landing site.

'Close in terms of a whole planet,' he added a hour later, grumpy and hot and dirty.

'A brilliant opportunity to witness ZLM Prime at close hand,' he finished, with biting sarcasm, within sight of Serendipity base almost four and a half hours after landing. 'All the dust, dirt, haemophilic aerial parasites and sand-in-boots you could want.'

By this time, in the small hours of the morning, there were no staff on active duty, bar two serving the graveyard shift in the communications shack. Deciding that a cup of tea was in order, even if it was the thin and unsatisfying mock-tea sprung from hideous genetically-modified lab cultures, the Doctor headed for the canteen Bay, and witnessed a dozing Rose suddenly jerk upright and alert.

'Doctor! You're back!' she blurted, immensely relieved. She practically sprang from her seat and gave the Doctor a huge hug in greeting, making his ribs creak in protest.

'Air – oxygen – breathe -,' he hammed, until she relinquished her grip and he could draw breath easily again. 'Phew! Vulcan Death Grip suddenly doesn't seem so bad.'

Rose hit him hard on the bicep, drawing a yelp of mock pain and indignance.

'Don't push it!' she growled. 'You take off without me, and then don't send any messages, and turn up eight hours late after a trip that should have taken an hour, if that, even!'

She recognised the measured, calculating gaze directed on her after that, the scrutiny coming from a humanoid alien with an intellect vastly different from hers, different and strange, an alien she moved alongside without really completely understanding –

'Rose. I'm sorry,' said the Doctor. 'Really.'

- and her paranoid worries disintegrated in a pico-second. He grasped her deltoids in a firm and commanding way and looked her directly in the eyes and repeated his line.

'Really?' she asked.

The Doctor nodded sincerely.

'Oh yes!' and he unhanded her. 'It was a dangerous temporal transit to get there, and an even more dangerous one to get back. I had to trade time for danger, you see. If I'd taken the Old Girl into that wrack on the way back neither of us would have made it through. So I flew conventional. Like your – what would it be? Like the Space Shuttle. Nice and safe, if a little slow.'

After that, he unlaced his shoes and allowed several ounces of dirt to fall from them, upended.

'Alas for me, I landed a tiny bit further away than I realised. Which added a couple of hours to my journey.'

'Find anything interesting?' asked Rose.

'Oh yes. This, amongst others,' he replied, subdued at the memory of an alien cemetery in orbit. Rose looked at the metallic cube he held out for inspection, bound with bands of copper and pitted with tiny holes arranged in a regular formation.

'Like that one from the secret room, innit? What does it do?'

'Given the care they took to try and get it out of danger, I hope it's a data-recorder. And that those crystals in emulsion were the recording media.'

A pretty safe guess, piezo-electric crystalline matrices used as a storage mechanisms, nothing too fancy.

Of course, as the Time Lord very well knew, there was no way to display the stored information, whatever it might be.

'Tackle that tomorrow, I think. I feel every one of my eight hundred and seventy years,' he groaned, stretching enormously.

'I thought you weren't even eight hundred!' complained Rose. Her reply was a knowing wink.

Display screens were at a premium on-site, meaning the Doctor needed to resort to a little creative "collection", sifting a bin of discarded equipment either too worn, badly damaged or inexpensive to bother repairing. The sour-faced technician caught him ferreting in the waist-high plastic container.

'What are you up to?' he asked, insistently. 'Looks like stealing to me.'

'Look harder, then,' muttered the Doctor, finally finding what he wanted – a junked thin-film monitor. Clutching a handful of other electronic refuse, he walked back to the bunker.

'Oi!' called the technician. 'Don't turn your back on me!'

Swivelling around to face the man, the Doctor continued walking backwards without missing a step, still focussing on the monitor and assorted cabling. He moved effortlessly over the ground and back down into the bunker whilst the ill-tempered technician frowned in annoyance and disbelief.

'How did you manage that?' asked Arpad, back as the ever-attentive shadow.

'Bunker entrance. Acts as a giant echo-chamber. You can hear anyone approaching behind you easily. Is there a workstation free?' and Arpad received the full wattage of the Tenth Doctor's effusive smile, persuasive and convincing in equal parts.

'I can find you one. You can even use mine, for getting the better of Kellerman.'

Maintaining the easy charm of a pleasant exterior, the Doctor nevertheless took note of how "Kellerman" was described, within earshot of others and with no attempt at subtlety. Kellerman was not liked.

'Kellerman?' he prompted.

'Kendal fnorping Kellerman, our Lowry specialist, buzi rohodas, the – oh.' Arpad paused in embarrassment, realising that he'd resorted to insults in Magyar.

'Well, I won't tell anyone if you don't tell anyone,' continued the Doctor breezily. 'Now – the workstation?'

Arpad's miniature computerised desktop sat in the corner of his dormitory cubicle, at an angle to the surrounding walls. The Doctor slid behind it and onto a stool with ease, using a microlens and prehensile surgical gauntlet to analyse the alien cuboid retrieved from the crashed shuttle.

'You know, Friday was more accurate than I was. She got the shuttle tonnage and overall dimensions very closely, which is unusual. Normally – ah, that's a reciprocating feed! – normally I better any human approximation by a considerable margin in terms of – and there's the power actuating fibre – percentage if not actual quantum levels – this must be a data bus line – so once again I need to defer to your native ability.'

Looking up at Arpad, all he saw was a giant fleshy blur.

'Whoops!' and he remembered to turn the microlens off. 'Right. I think I've got this box of tricks sorted.'

Arpad, recalling the phrase "human approximation", merely nodded with cautious wonderment. Apparently this not-Auditor could pilot a super-high acceleration rocket-ship, perform geophysical assays, carry out intricate electronic analysis and effortlessly get the better of the expedition's more unpleasant members. Obviously he was human, but – just how human was he?

He looked on as the stranger effortlessly dissected cabling leading into a discarded thin-film monitor, unwove it, then welded the new ends together in different combinations with his sonic device and threaded them into a novel block of metal.

Nothing happened initially. This didn't seem to bother the Doctor, who spun out more cabling from an insulated core, before adding a rheostat unit and a plug.

Ah! Of course, realised Arpad. The strange conglomeration needed power to work.

'We'll start low,' announced the Doctor, keeping the rheostat at the lowest power setting and only gradually increasing it. Arpad drew in his breath sharply when an image evolved on the display: a language, in symbols unknown to him. The image swam before stilling, a function of the damaged display unit.

The Doctor felt quietly vindicated. He didn't recognise the language, either, and he knew every one in this arm of the Galaxy. Producing a matchbox, he daintily opened it to reveal a cluster of tiny crystals – originally loaded in the recording device aboard the Trinarian spaceship.

'Could you go and get the crystals being kept in suspension for me?' he asked Arpad. 'Let's see if they work, too.'

Before the Hungarian returned, the Doctor had used the medical gauntlet to slip a crystal into a socket of the recording unit.

No result. He took the crystal out, reversed it and tried again.

'Result!' he murmured. A menu appeared on the screen, unguessable in content but obvious in appearance.

Rapidly sorting crystals and seeing if they worked, he found that one in three functioned. When Arpad returned with the Miller emulsion, he discovered a far lower survival rate; only one in five.

'Make yourself useful, Arpad. Get a notepad and a pen and labels. We're going to catalogue what we've got here.'

Satisfied at a degree of procedural rigour being applied to the bizarre collection of electronic junk, Arpad nodded and dug out the stationery from his personal effects.

Roj's instructions to keep the Doctor and Rose separated were still being enforced, if a little laxly, so she got an invitation next morning to accompany Montag out to Baby Bunker One. TEST Rat 3 came with them, bobbing in that peculiar fashion the intelligent rodents had when excited.

'Not much to see out there, really, but we use them as alternate data points with the solar telescopes, plus Graham likes to use them to go roving from.'

Graham Chadwick was the expedition's Number Three, a geologist specialising in stratigraphy, frequently away from Serendipity base. He had been on Mars, an achievement Montag seemed jealous of.

As they drove away from Serendipity base the terrain became less empty, filling with stands of timber and shrubbery, all of which seemed infested with the grotesque faterpillars. Rose wrinkled her nose at the sight of them, glancing at the TEST rat and deciding that it might not be cute and cuddly, but it still came from Earth and possessed a certain familiarity.

When they got to the Baby Bunker, it proved to be rather underwhelming: merely a large fusor-created cuboid, minus one wall. An angled ramp at the rear led to an underground chamber that now stored various mission paraphernalia, including an occupied camp bed. The upper floor was empty so the visiting pair went down the ramp and into the chilly, dank air of the underground chamber.

Rose shivered. The gloom was accentuated rather than dispersed by a set of floodlights set up in a corner.

'Hoy! Barry! Wake up!' shouted Montag, kicking an empty metal storage case and creating an unholy racket. 'Graham? Come on, we're here to get you back to camp!'

Still the figure didn't stir. Rose wrinkled her nose again, this time at a penetrating and unpleasant smell. Montag noticed it, too, and suddenly looked alarmed.

'Graham, are you okay?'

Rose noticed an absence – the blanket covering the sleeper didn't move at all, meaning that they weren't breathing. She whispered this to Montag, who darted over across the store-strewn floor to the camp bed and whipped off the blanket.

'Ohmygod!' yelped Rose at the sight of the camp bed's occupant: a rotting, anonymous corpse clad in one of the mission's boilersuits.

SEVEN

Once more, Roj felt unhappy. His wife had clashed with Rose Tyler, who now stood accused of being a colossal snob with more money than brains and what exactly was she doing snooping around anyway not to mention that plabby weirdo the Doctor and what kind of Doctor was he anyway –

Then again, he also needed to consider that aside the Doctor had made about a spy within the mission. Technically, he, as Mission Leader, was required to regularly report back on the Moral and Political reliability of his staff. In reality his distaste for the task meant he simply reprinted a sheet of "100 Reliability" for everyone and sent that with the Lowry transmissions. Surely the Grey Em – The Administration – wouldn't bother to have a spy within such a small group?

Quite beside his marital discord, there stood the Data Deficit. With the discovery of Arpad's "Trinarians", another 5 per cent had been added to their collated information, meaning that the mission had slipped to 79 per cent deficit.

Kellerman hadn't been helpful, either, the arrogant little bald mooj. He patronisingly informed Roj that ZLM Prime's orbit prevented any more information from being sent back to Earth via the Lowry coil, and that the two hour orientation sessions for the dish were the bare minimum possible. Even so, with the huge distance to the receiving stations back on Luna, there would be a significant drop-out of information.

'Good afternoon!' said a cheery voice, heralding the Doctor and Arpad. The Doctor looked cheery, Arpad looked – stunned. He was pushing a small work trolley that held a pile of reconstituted electronic junk.

'Kendal mentioned he'd caught you nicking from the reject bins,' commented Roj sourly. 'What now? Come to throw a Number Nine nickel-chrome spanner into my works?'

'I've come to demonstrate the products of my tinkering genius,' said the Doctor, sorting out his electronic impedimenta into a semblance of order. Pride of place went to a silver cube banded with copper, dotted with small sticky labels above tiny holes that to dotted the cube.

'That's the gadget from the hidden chamber,' accused Roj, only for the Time Lord to wag a contradictory finger in front of his nose.

'Wrong! Similar, except this one came from the alien shuttle crashed on one of ZLM Prime's moons. Which I have now decided to call Elysium.'

The casual revelation of where the Doctor had been, what he'd been doing and what he'd found forced Roj to sit down abruptly, making his chair creak. He found the Doctor passing him a set of glossy sheets of photography paper.

'Took these up there with the suit camera.'

The landscape of Elysium was bleak in the extreme: all harsh overlit wasteland, sharp battered rocks, inky shadow and low peaks. A big silvery object at the end of a long gulley turned out to be an alien craft, fusion-powered, landed so hard or badly that it never took off again. Next to it sat a stellate graveyard full of alien-scripted headstones. The ship's airlock door was enormous, the interior underlit and battered, and five more huge alien corpses decorated the control cabin.

All striking stuff, proof that the interfering stranger was considerably smarter than Roj gave him credit for.

'I – okay, you've proved an alien ship made it's way off-world and crashed. What's all this electronic junk you've brought in?'

In answer, the Doctor unrolled a long strip of fabric with tiny crystals taped along it's length, each with a number written next to them.

'Took us a couple of hours but I think we've got the correct chronological order,' announced the Doctor proudly. He inserted the first crystal, turned on the power and held the display upright.

The screen shimmered into life, with a dark blue background. A blizzard of static jumped and slowly resolved into a page of text, a spikey pictographic scrawl laid out formally. For half a minute the text scrolled upscreen.

'We think that's a list of their personnel. Two hundred and forty five names, arranged in a rank structure,' explained Arpad.

Roj gave a low whistle of surprise. Two hundred and forty five of them! Big expedition.

From a list of names, the alien script became a series of dense blocks, reading from left to right, until the sigil of a sun superimposed over a lightning bolt appeared. Suddenly, the viewpoint became one of a subjective camera, moving out from a ramp and onto the surface of ZLM Prime. Column after column of Trinarians marched in step down the ramp under the camera's eye, forming a giant circle ringing their spaceship, whilst the camera operator stood aloof. The big aliens stood impressively still, harnessed and equipped with pouches and strange devices, and what looked like weapons, both guns and bladed.

At a shouted word of command, the assembled alien circle hefted their weapons and began firing, moving away from the spaceship. Shrubbery, insects and animals all caught in the destroying wash of violet-white energy shrivelled to nothing. The circle of death moved outwards until there were gaps of a hundred yards between figures. Another shout of command, and the firing stopped. Another shout and the circled contracted back to the spaceship, marching in step.

From an amorphous mass, the Trinarians shook themselves out into small groups of equal size, edging and hedging until they formed a giant tri-lobed parade formation, with a small group in the middle, speaking forcefully in Trinarian.

The sun-and-bolt sigil appeared again, and the screen blanked out.

'Wow. Not big on ecological conservation, are they?' joked Roj. 'I suppose that explains why this site is so barren for miles around.' He felt strangely proud that they kept Serendipity free from vermin and mega-orthoptidae thanks to the TEST rats, who were a whole lot less destructive than rings-of-death wielding ray guns.

'Notice their military organisation,' noted the Doctor. 'All armed. Directed energy beam weapons, long knives, body armour, and a willingness to fire first and not ask any questions.'

The second crystal showed a giant fusor assembly going to work on the stone outcropping forming the raw basis for Serendipity's bunker. This happened to be quite dull, and long, so the Doctor sped it up by tinkering, until the pristine bunker finally sat, or squatted, on the blasted heath the Trinarians had created. Added inserts at each side of the screen showed the two miniature bunkers being created, each amidst another expanding circular formation of aliens blasting anything in front of them into oblivion.

Via time-delay camera trickery, a framework of scaffolding and support struts took place on both of the minor bunkers, with a larger version being erected atop Serendipity. A giant parabolic dish off a corner of the site seemed to hint at the pylon's purpose: support for a gigantic transceiver. Holes were drilled in the Serendipity bunker casing with what seemed to be ultrasonic lances, and armoured cabling fed in to the unguessable mechanisms beneath.

Again, the sun-and-bolt sigil came up, indicating the end of a recording session.

'So the Baby Bunkers had an operational purpose,' commented Roj, now truly interested in the recordings. 'We always considered them to be a sort of emergency refuge.'

The Doctor shook his head.

'These aliens came here for a very specific purpose, Roj. You don't see them setting up any kind of exploratory procedures, do you? No. It's straight into site-clearing and construction.'

Roj leaned back dangerously far in his chair. True enough, he pondered. The Trinarians instantly set-to in clearing a site and getting their fusor-building underway, then erecting giant aerials. No bothering about ecology, or their impact on the local flora and fauna, or anything except their mission.

The next recording jumped and flickered a lot, making watching an uncomfortable experience. Time had elapsed, or there were faulty crystals between the previous recording, since the bunker now sported an immense parabolic dish. The scene jumped to the bunker interior, showing huge displays and control consoles and suspended three-dimensional models of ZLM Prime and ZLM. An alien voice underscored this montage, doubtless explaining what was what and why it was – all lost on the watchers.

Hmm. You know, I think I begin to detect a pattern to this vocalisation, said the Doctor to himself. If they match displayed script to words I may be able to begin a rough translation. Ah, sometimes I impress even myself!

The film display wound it's way into the bunker's lower level, where an immense power plant hummed and glowed, occupying every square inch of the structure.

'Anti-matter powered fusion generator,' mused the Doctor aloud. 'You know, that puts out a lot of power. An awful lot of power. These lads were certainly serious about their project.'

Mentally, he calculated that the plant put out – as a fair guesstimate – energy in the peta-joule range. Ten to the fifteenth power joules per millisecond – enough to boil off the entire atmosphere of ZLM Prime in a few hours if misdirected.

And this was a military expedition, rather than any straightforward scientific endeavour. Why did they need such literally astronomical energy outputs?

The next crystal began with a variation on the sun-and-bolt sigil – this had a triple-legged symbol bizarrely resembling the Manx flag. It was lots of short clips of Trinarians doing mundane activities; digging long trenches, playing a game of handball, wrestling, playing dangerous games with rampant sillipedes –

'The Trinarians at play,' concluded Roj. 'Next crystal.'

Next in the film record was the construction of small tracking antennae – which the Doctor guessed were a combination of detector and weapon – in a self-contained package, several of which were drilled into position on the bunker roof, with one each at the Baby Bunkers. Protecting their big dish, pretty obviously.

Roj chewed a thumbnail slowly before speaking.

'I wonder. Doctor, we always considered that these aliens – Trinarians – came here to study ZLM for the purposes of scientific research. Why would a military expedition come here if not for that same reason? I concede that - ' and he paused as his wrist-phone vibrated and the display glowed red.

Red, he sluggishly realised. An emergency.

Belatedly, he noticed one of the TEST rats tugging at his boilersuit trouser cuffs. TEST Rat 3.

'!!!' it signalled. 'Murderdeathkill.'

In a reflex action, Rose gagged at both the sight and smell of the decaying corpse lying on the camp bed. Montag backed away, making a sour face at being so close to the body. The TESTer cowered under a folding chair, not daring to move.

'What happened?' asked the young woman.

Montag bit his cheek until blood ran before answering.

'This looks to be the size of Barry. Graham must have – fnorp, I don't know, gone mad, had a fight, quarrelled over something. Killed Barry, then left the body here. He might have gone and killed himself – no, what am I saying, he's been on the radio link to Serendipity.'

Montag looked around the underfloor storage space, noticing that there didn't seem to be any disarray or signs of a struggle. No blood, no sign of a murder weapon.

'They look to have been dead for weeks,' said Rose, remembering countless episodes of "CSI" and "Bones". Her companion shook his head.

'Don't count on it. I'm not a pathologist, but the biology people say that micro-organisms here on ZLM Prime don't exhibit their larger relative's reluctance to eat humans. This body might only be a day old.'

Rose's sharper hearing detected a sound from above, and she caught sight of the rat wedging itself even further under the chair. She instantly froze, finger on lips, warning Montag.

Over here, he mouthed, pulling at her arm. They tiptoed with celerity behind a large storage rack that stood a foot away from the bunker wall. Stay quiet! he added.

Rose nodded in silent agreement. Footsteps echoed down the ramp from above, and a silhouette came into view, stark and dark against the spotlights. With an intake of breath, the figure trotted across the bunker floor to the camp bed, as Rose realised with muted horror that they'd forgotten to replace the blanket properly.

'Follow me,' whispered Montag, edging out into full view of the new arrival. His confidence seemed to follow from getting his hands on a yard-long piece of metal piping.

'Hello Graham. Come to inspect your handiwork?' he barked.

Graham Chadwick nearly went into orbit, so extreme was his reaction to Montag's challenge. After recovering from near-terminal shock, he leaned back to survey both Rose and Montag.

Hardly a threat, considered Rose. Five six and ten stone - if that. Glasses and a mousey hairstyle.

'Lord above, don't bloody do that! I nearly died!' complained the geologist.

'Unlike your victim!' riposted Montag.

'What victim would that be?' asked a voice, as another man came down the ramp and into the lower bunker level.

'Oh. Barry. You're - alive,' stated Montag, his voice now shot through with doubt.

'Don't sound so disappointed!' quipped the latest arrival, as weedy and unthreatening as Graham, except that he had very little hair left.

Graham pointed at the corpse.

'You thought that was Barry and I'd done him in? Well thank you!'

'If it isn't Barry, then who is it?' asked Rose.

Graham looked embarrassed. Barry looked blank.

'We don't know. We didn't bring any biometric scanners with us – no need. There's no way of identifying a body so badly decomposed without DNA sample kit. Which we don't have.'

'How did you find it?' asked Rose.

Graham explained that he'd been doing stratigraphic analysis of the nearby riverbank, where the soil layers were conveniently arranged in a nice, neat accessible vertical format. Except at one point, where a hollow had been dug into the soft sandy ground and then refilled. From the edge a fragment of fabric protruded, and true to his inquisitive nature, he'd pulled hard on it, eventually using both hands to haul a concealed corpse from the hiding place. Not knowing what else to do, he'd put the body in the bunker basement, away from any roving local wildlife, then returned to the riverbank with Barry to see if there were any more remnants or clues.

Rose felt as stunned as the three men looked. A murder – it had to be, nobody would panic and bury a body in such fashion over an accident or a mistake. She shivered involuntarily, realising that one person amongst the mission had gone temporarily insane, mad enough to kill, then be rational enough to conceal.

An un-nerving thought, that one of the people she'd been rubbing shoulders with was actually a killer.

'What should we do? What should we do?' asked Graham, clearly at his wit's end.

'Put the body in a bag and seal it. The killer doesn't know we know about this. Conceal the body until we can investigate more closely. And we need to get in touch with the Doctor,' concluded Rose promptly, her experience of difficult situations on a dozen planets and different eras standing her in good stead.

With difficulty, they got the body into a big canvas holdall, then stored that in the Rapid Rider's lockable and cavernous hold. Rose, feeling obliged, cossetted their rat from it's hiding place beneath the chair and into the vehicle.

'Feel bad' it signalled. The energetic bobbing motion that the rats displayed when interested or expectant had vanished, replaced by a worried crouch.

'Don't tell anyone else what's happened!' cautioned Rose. 'You two come with Montag and me when we get back to Serendipity.'

Montag sent an emergency signal coded to Roj on his wrist-phone and the quartet tried to manage a casual, unbothered air as they parked and walked into the gaping maw of Serendipity.

Arpad felt untypical sympathy for Roj, whom everybody assumed contributed personal profiles to The Administration by way of keeping tabs on them. The Mission's leader now had to cope with the influx of new data from the Trinarian recordings – and then a TEST Rat arrived, signalling alarming news. Shortly after that, Rose, Montag, Graham and Barry also arrived, all looking nervous and worried. The Doctor apprised things immediately, leaning in to listen to Rose as she whispered to Roj.

'Murder!' blurted the astronomer after Rose finished speaking, making Arpad lean in closer in sheer astonishment.

'Yes. We can't tell who it is, the body's too badly decomposed. Don't look so smug!'

Roj shook his head. This time he was ahead of the game, instead of that Doctor feller or this girl.

'Impossible!'

'It isn't impossible, you steaming great nit!' hissed Graham. 'I dug that body out of the riverbank myself. Don't patronise me!'

'I saw it and smelt it,' added Montag, glancing sidelong at the Doctor, who had clapped his hand to his brow in surprise.

'Well, for there to be murder involved, a victim has to be murdered,' continued Roj, sharply. 'And nobody is missing.'

After tapping away at the keys, he threw his screen around on it's base, and displayed the full staff list for the Mission.

'You can count them if you doubt me, but all forty-four are there. Nobody missing, no murder.'

'Whose body was it, then?' asked Graham, baffled. Roj shrugged.

'Dunno. A stowaway?' he suggested, without thinking.

'Who went un-noticed aboard a starship with no spare space anywhere? For six months?' riposted Montag.

'Show me!' replied Roj, getting annoyed at this impossible insistence and occurrence. 'Show me this - corpse!' and he suddenly lowered his voice in realisation of what he was saying and what it implied.

Rose led the way outside, a cowering TEST Rat following her to the Rapid Rider.

Which had gone.

'Who moved it?' asked Montag plaintively. Nobody had witnessed the vehicle being driven away, or rather if they had then they didn't pay any attention to such a completely normal event. A short search by the seven humans and single rat located the high-speed tractor behind the Defensive Dyke's outer wall.

'Mooj!' cursed Montag, coming up behind it and seeing the cargo hold lock smashed open.

'Empty,' he declared, peering inside the gloomy space. 'Removed by someone.'

A disbelieving Roj looked into the dark storage space, noticing a clammy smell and bits of dirt scattered about.

'Okay, the tractor got taken by one of our staff. Then they parked it here for some silly reason. No body, no evidence, no murder.'

Graham and Barry both vocally expressed their self-disgust at failing to take a picture of the corpse with their wrist-phone, which might have persuaded their leader. Roj remained silent, curling his lip with annoyance at the silly charade, before the rat tugged at his trouser cuff again. He kicked it away without thinking, and the big rodent scampered to Rose.

"Smell" it signalled. "Bad", and darted beneath the Rapid Rider.

'Made a new friend, have we?' joked the Doctor, as Rose got down on all fours to look under the suspension. 'What!' he added as he saw her musculature tighten with surprise.

Rose backed away and stood up.

'There's a pile of ash under there, still glowing. And it stinks to high heaven, too.' She looked coolly at the rat when it emerged. 'Thanks for that. Number Three.'

Squeaking with delight at this praise, the rat bobbed and ducked. Montag got into the cab and drove the tractor forward a few yards, revealing a pile of ashes. White at the edges, barely glowing in the centre, the faint smoke it gave off had an evil taint.

Rose saw the Doctor's pose stiffen and intensify, his eyes gleaming with concentration and worry. Contrarily, Roj seemed less interested than before.

'They parked directly over flammable material and the exhaust's heat set it alight. Happened before a few times.'

'Quite right,' grinned the Doctor, relaxing plausibly to all except Rose, who recognised a steely glint in his eyes. 'Reginald Molesworthy, where are you now?'

Barry, Graham and Montag argued sotto voce all the way back to Serendipity, with Roj ignoring them and striding out in front, the very picture of an aggrieved leader. Rose and Arpad followed the Doctor, who stalked determinedly after Roj. Before they returned to Roj's partitioned quarters, the Time Lord casually remarked that he'd got more information about the Trinarians, would they be good enough to sit in on his presentation with Roj? Real live footage of the aliens in action, from their own recording equipment. Naturally the others agreed. How or why would they refuse such a reasonable request?

When their septet huddled into Roj's space, the Doctor hauled a sliding partition door into place to prevent anyone else from joining in.

'You're up to summat!' whispered Rose as he passed, getting a solemn wink in return.

'Could you get the Trinarian gear running again, Arpad?' asked the Doctor, seeming to fiddle with his shoelaces, perched on Roj's folding camp bed. Briefly, the trilling whir of his sonic screwdriver came from his stooped position, followed by a loud clack as an unseen object fell open.

When the Doctor stood, he cradled Roj's plasma bolide carbine, and in such a way that implied he knew how to use it.

'Right!' and his voice had a hard edge to it, an underlying steel that warned his audience not to try anything silly, heroic or hasty. Rose recognised it as his Don't Argue voice and remained quiet and still.

'What the fnorp are you doing!' gasped an utterly amazed Roj.

'Keep it quiet,' warned the gun-toting Doctor. 'No interruptions or extra guests wanted or needed. Firstly, you're the chief astronomer here. Did any of your staff report seeing a purple fireball in the past few months or weeks?'

Under other circumstances, Roj's loose-jawed incomprehension might have been amusing. He stared in silence, still not able to process what he saw.

'Yes,' answered Graham. 'A few of us saw one two months ago. Totally unexpected, so we didn't have any recording gear to image it.'

'More bluish-white than purple,' added Barry.

'Did you kill that person?' asked Roj, in a strained voice. His prior disbelief seemed to have vanished.

'Don't be daft!' retorted the Doctor. 'We've never been out of sight of your staff since we arrived. No. The guilty party we're looking for is much, much more dangerous than we realised.'

Blank looks all round. The Doctor tightened his grip on the carbine and carried on.

'Your team has been infiltrated by a Rutan.'

EIGHT

Expressions of startlement came from every lip. Sighing with relief, the Doctor carefully put the carbine back in it's box, wondering if he'd have been able to use it anyway; even holding a weapon felt un-natural to him, and his hands itched in sympathy with his conscience.

'Sorry for that. It might have replicated and one of you might have been a Rutan.'

'I did wonder,' said Arpad, drily. 'I mean, none of us drove that tractor off, did we!'

'Why a Rutan?' asked Roj, getting his brain into gear. Graham and Barry exchanged shrugs with each other.

'They can mimic other life-forms,' confirmed Montag. 'Shapeshifters.'

'Exactly!' agreed the Doctor. 'That's why you have – had – a body but nobody is missing.'

Rose shuddered. This was even creepier than the possibility of sharing space with a murderer. Shades of that awful film set in the Antarctic with Kurt Russell, the film that gave her nightmares when she watched a pirate copy at Kirsten's.

'I know what you're thinking,' commented the Doctor, looking at her. 'No, not like "The Thing". This Rutan will have spied upon and studied it's victim for days, maybe weeks, learning their speech patterns and behaviour before getting rid of them.'

Not helpful! shivered Rose.

'It must have realised you'd found the body when you came back to Serendipity. So it stole the tractor and destroyed the evidence.'

Puzzling, that, wondered the Doctor as he talked. Rutans generated a massive electrical charge that could incinerate the human body – evidenced by that pile of ashes – so why go to all the effort of burying the body in the first place?

'Okay, so we know what our danger is - ' began Roj before the Doctor interrupted him.

'Wrong! You don't know what this Rutan is after, but their method of operation is to infiltrate and subvert, to destroy from within. That's what you have to contend with, not merely a murderer.'

Once more Roj fell silent. Clearly, the stress and strain of his newly-acquired responsibilities didn't sit well or easily with him. Why me? ran through his mind.

Why here? ran through the Doctor's mind. The Rutan Hive had suffered tremendous setbacks and defeats in recent millenia, sufficient to force it onto the defensive against the Sontarans. So, given that resources were stretched, why send a scout all the way from the Debatable Zone and risk combat with the nascent human empire of The Administration?

'Could it be after whatever the Trinarians were doing?' muttered Roj slowly, making people look at him, not knowing if he was talking to them or only to himself. thinking his way before asking any more questions. 'No, that's daft, they've been gone for eight hundred years.'

'Okay. I know that you are all human,' explained the Doctor. 'If any one of you had been a Rutan, you'd have been forced to attack and kill us all to conceal your presence. From now on I recommend that we try to operate in teams of at least three to prevent any more substitutions.'

'How do we track it down?' asked Rose, worrying that only these people here might very well be human, and hoping that the rest of the mission still were.

' "We" don't track it down. Attempting that will only cause it to simulate another victim. Prevention first. Allow me to come up with a foolproof method of detecting our intruder.'

A few glances were exchanged at that; Graham and Barry looked mutually skeptical.

'Great! Fantastic!' snarled Roj. 'Murder, Rutans, hordes of dead aliens and a data deficit that gets bigger daily! Any more good news?'

Right on cue, his wrist-phone rang. When he took the call it was his wife, Christy.

'ZLM is beginning to become unstable,' the tinny voice declared. 'Just thought you should know.'

Roj threw his hands up and stalked out of his cubicle to get a drink of tea, muttering in annoyance.

'Anyone fancy carrying on with the film show?' enquired the Doctor, and then had to explain what the battered collection of junk sat on a trolley actually did. He replayed the crystal recordings from the beginning, allowing Roj to potter about on a display with staff lists.

Then, when playing a new recording, it became immediately apparent that there was a gap in the crystal's records. The Trinarians were filmed running back and forth in the bunker, as a voice-over described a panic in progress, unseen to the audience. Then the filmer pounded back up the entrance ramp, escorted by half a dozen aliens wielding the big rifle version of their ray gun, out onto a weirdly distorted landscape. A small group of aliens with elaborate braiding stood directing dashing figures around the camp, consulting mapboards.

Rose couldn't realise why the picture looked so odd, before peering closer and wrinkling her brow.

'You need to adjust the monitor,' commented Arpad.

The Doctor cradled one elbow and frowned, too.

'That's not a display problem. That's ZLM in flare-up mode.'

A burst of shouting and the ripping discharge of energy weapons came over the speaker unit, while the filmer changed direction and headed south of the bunker, the picture jogging and bouncing whilst he ran.

In seconds, the picture showed a knot of aliens, stood at a respectful distance from a fuming mound of shrubbery, reduced practically to ash by their weapons.

Weird! thought Rose. Unless there was a bogeyman hiding in the bush.

Silence fell over the faintly ridiculous scene, only the filmer speaking in that unintelligible alien language. The picture returned to it's previous location, where suspicious and alert aliens patrolled in trios, pausing every so often to pull down helmet eye-pieces and scan the landscape. Small piles of ash in the distance marked the location of their earlier handiwork. Once again the picture moved on, in a land where the shadows swam erratically in fitful sunlight, glaring and hatefully hot. Suddenly the picture jerked alarmingly, as a shriek came from what must be the filmer and the escorts whirled around in surprise. The picture span, hit the ground and the recording abruptly stopped.

The last pictorial crystal wasn't a seamless montage as the previous ones had been, and once again there must have been a gap in the records. Trinarians were shown hastily outfitting a chamber with equipment – that same hidden chamber the Doctor had uncovered – whilst others rushed past with armfuls of equipment to the entrance ramp, appearing seconds later unburdened. Static fuzzed the display, resolving into another scene, that of the subterranean level, now empty of the gigantic fusion generator. A few broken welded stanchions were all that remained.

More fuzz and static, and a mobile fusor unit moved in to seal off the chamber, where three Trinarians gave a solemn salute and seated themselves at the island consoles. Then the scene cut without any transition to an exterior view, showing the point of view of the alien running with huge strides towards a tall, sleek spacecraft that towered on strut-like legs, accompanied by the ripping screech of energy weapons firing non-stop.

The next crystal, one of those recovered from the derelict alien spaceship, consisted of endless scrolling lines of alien text, as did every one after that.

'Any comments?' asked the Doctor.

'You deduced what that chamber was for. Right on the nail,' congratulated Arpad.

'Yeah. Shame we didn't see what the Trinarians were actually fighting against,' mused the Doctor. 'Aha! You know, I think I can place that scene where they rush to the burning bush.'

He did, too: headed due south from the bunker, given an average stride of one and a half yards, travelling for fifteen seconds, he could locate the spot to within a foot – and set out to do so.

Rose and the others followed.

'Surely there won't be anything left, after all this time?'

Arpad saw his wife, Davinia, sitting red-eyed in the canteen area amongst a group of gloomy and sombre people as they passed by. He darted off to console her and find out what the problem was, returning in an equally sombre mood of his own.

'Probably not, Rose, still it's worth a try. Trouble?' the Doctor directed at Arpad.

The Hungarian sighed.

'Dav's been listening to that lot too much. They all think ZLM might be going supernova this time.'

The Time Lord strode on, shaking his head.

'Nah! Not a chance. Decades away, at the worst.' He glanced back at the worried husband and grinned. 'Honestly!'

Strangely, Arpad found this reassurance from a practically unknown stranger whom they knew nothing about, to be persuasive.

'Well – okay, if you say so.'

The troop, minus Roj, left the air-conditioned cool of Serendipity bunker and followed the Doctor as he lolloped carelessly over the netting that prevented excessive erosion from tracks or feet. They drew nearer an array of pallets stacked ten feet high, all wrapped in reflective blue plastic. The Doctor began to measure his strides more carefully, finally coming to a halt at the bulk of a palletised load.

'Well now, if there was a trace – it's sitting under all this.'

He bent down to examine the earth under it's netting protection, just as a long zzzzzip sounded, terminated with a sharp ping! as a hole appeared in the pallet side, where the Doctor's lanky frame had been a split-second before.

'How peculiar!' he exclaimed, standing up again, as a second whining ended in another hole appearing where he'd just been bending down, sited at head level.

'Get down!' yelled Rose, diving for the Doctor's ankles and knocking him flat in a passable rugby tackle. 'Those are bullets!'

One undignified scramble later, the little group stood in the lee of the pallet.

'Thanks,' whispered the Doctor quietly. Rose flushed a little.

'Not bullets, technically,' said Arpad, ducking round the corner and back again. 'Induction pistol slugs. No sound made when fired. Sub-sonic, you see.'

Graham looked darkly at the biologist.

'They can still kill! Who the hell is shooting at us?'

Long, weighted seconds passed, becoming minutes until they decided the mystery shooter had gone.

'Some bloody mystery!' snarled Barry. The hostile expression looked strange on the normally placid scientist. 'Mike's the one with an induction pistol!'

He and Graham set off at a run for the bunker, Rose following when the Doctor discreetly nodded after them and then at her.

'Are we up to anything dangerous?' asked Montag, noticing the Time Lord's relaxation once the teenager had left.

'Possibly,' said the Doctor in an abstracted way. He bent to look at the two holes in the cargo pallet, then stuck his sonic screwdriver into each in turn, getting a rough reciprocal bearing.

The Lowry shack. When they got there, the shack was locked. Thanks to the netting, there were no traces of footprints outside either.

'I'd like to look inside, check that there really isn't anyone hiding in there. Montag, would you mind staying here? Ta. Who has the key?'

'Kellerman,' snorted Arpad.

'Splendid! A man most unloved. Come on, let's see him.'

Ruefully, Arpad led the way. Once back inside Serendipity, he caught the nearest TESTer and told it to lead them to Kellerman. The rat bared it's teeth and scampered off into the maze of partitioned cubicles, stopping to indicate with a flick of the paw and was off again.

I don't believe it! mused the Doctor to himself. Even the rats don't like this man.

Kellerman lay half-on, half-off his bed, swilling from a bottle, scratching his belly and reading an electronic notebook.

'What d'you plabbies want?' he grunted as they entered the cubicle, then burped loudly.

'The key to the Lowry shack,' replied Arpad.

'Is that beer?' asked an incredulous Doctor.

Kellerman belched again, reached into his unbuttoned boilersuit pocket and threw a long magnetic key at Arpad.

'Don't lose it, you Magyar mooj.'

Arpad caught the key whilst muttering in Hungarian, then explaining. Kellerman had brought out a pocket still as his personal effects, that small allowance of cargo weight that the mission staff were allowed.

Predictably, the Lowry shack was empty when they unlocked it to check for hiding assassins.

Having remained at his desk when the group of film-watchers left to chase the faintest traces of any possible centuries-old remains, Roj shook his head, feeling like burying it in the sands.

Things were so bad they couldn't get any worse, could they? He felt like sharing the news about a Rutan with Mike, nominally the mission's second in command, except Mike could be a Rutan in disguise.

Bah! That stranger the Doctor was responsible for all this disastrous chaos!

Coming to a decision, he went off to locate Mike, busy working in the Biology Bay. The biologist, his wife and Zusanna were in the process of dissecting a new variety of Kink Bush. In preparation, they had flash-frozen it with a liquid nitrogen spray before sectioning the plant in a monomolecular guillotine. Delgerdzaya, Mike's wife, had built the guillotine from scratch, doing a very good job, too. Roj looked on with appreciation as the doctor sliced the plant longitudinally, Zusanna deftly taking the slices and stacking them alternately on sheets of sterile plastic.

'How's it going?'

Mike unscrewed a microlens from his left eye.

'Interestingly. We've discovered a rudimentary network of fibres analagous to human neurons.'

Roj stared. A plant with brain cells? Zusanna laughed, only to get a stern frown in return.

'You ought to get a move on with these analyses, Mike. I want them completed as soon as possible so - '

'What about the data deficit?'

'I want to know how much extra data we have to transmit once your research is complete, and you're not going to complete it at this rate.'

Mike made a face and heaved a sigh of mild exasperation.

'Roj, I remind you that I am not a multi-disciplinary expert, nor are my staff. This is not my field. I'm doing the best I can. What - '

Before he could continue, Graham and Barry barged in through the double-sealed isolation doors, Rose at their heels. Both geologists looked angry, Barry especially so. Rose looked troubled.

'The idea of those doors is to keep this area sealed,' patiently began Mike, before reeling back as Barry threw a punch at his head. Graham restrained his partner, if with a degree of difficulty. Delgerdzaya gave a squeal of fright before picking up a metal specimen tray and moving to defend her husband.

'What are you DOING!' yelled Roj, unrestrained in his anger.

'Shoot us, eh?' snarled Barry, wriggling and struggling to get loose from Graham. 'Aiming for anyone in particular? Or just anyone you got lucky with?'

Mike rubbed his cheekbone, which glowed red and would bruise wonderfully within an hour.

Roj took charge by grabbing Barry's windpipe in a ferocious grip.

'If you don't calm down I will choke you to death! Believe me I'm angry enough to do it!'

Rose hastily jumped in.

'We were out by the cargo pallets when someone fired two shots at us, from an induction pistol.'

Barry stopped struggling, sneering at Roj and Mike.

'When?' asked Mike.

'Just now. A couple of minutes ago.'

'I've been here for the past ten minutes with Mike. It wasn't him,' said an icy Roj.

An equally icy Delgerdzaya stalked over to the recording camera mounted on a wall. She switched from "record" to "display" and reversed the recording, playing it back for half an hour's worth of elapsed time. She, Mike and Zussana all darted about in comical speeded-up fashion, backwards.

'Oh,' was Barry's less-than-expressive commentary.

Roj told Zussana to get the induction pistol in it's case, from beneath Mike's bed. When she returned the biologist unlocked the case, and there lay the massy, ugly weapon, complete with ten clips of slugs. Cold, oiled and unfired for months.

Delgerdzaya applied ice to her husband's injured cheek, which he accepted with less than complete grace. Rose ushered the sheepish geologists out of the Bay. Zusanna shook her head and left to get a bite to eat, as she put it. Did anyone want some? Mike's wife shook her head and left to get a shower.

'This place is turning into a madhouse,' muttered Mike to the air.

'Yes. But it never had very far to go,' responded Roj, replying over his shoulder whilst leaving the Bay.

Mike stood and craded his cheek with the ice-pack for a minute, ruefully feeling the inside of his cheek with his tongue.

Roj came back in, seemingly as an afterthought, lowering his head and giving the biologist a knowing look.

'Okay! Okay, I'll get on with an irradiation programme with the Kink Bushes we have, alright!' and the biologist tutted, grumbling under his breath in Mongolian. He began to unfold a lead-screen cubicle for the plant, getting ready to place it in the Hard Radiation Chamber. 'See? See how I'm getting on?' he complained, to a grunt from Roj, who walked out again.

Heel-dragging their way back to the bunker, Montag and Arpad felt uncomfortably exposed, even if the Doctor went striding on ahead without a care. The external temperature seemed to have increased, which might have been psychosomatic, or not.

At least, without an apparent care. The idea that a mysterious assassin, who might be different from the mysterious Rutan intruder, had tried to kill him – or perhaps another of the little group clustered around the pallet base – preyed on his mind. Who would try that?

Balancing that puzzle, he felt mildly satisfied that the Trinarian's recording crystals yielded up so much information. If only there weren't such significant gaps in their sequence!

The acoustics of Serendipity bunker played tricks on the hearing, he decided. Or maybe there was a loose vent in the air-con plant that simulated a muted howling?

Cocking his head to one side, the Time Lord looked questioningly at Arpad, who returned the gaze nervously.

'I don't like that sound,' muttered Arpad, ending his comment by nearly crossing himself.

The howling stopped, having caused several people to begin moving towards it's source, the Biology Bay. Seeing that the Doctor meant to investigate, half a dozen mission personnel trailed after him and through the double doors into –

- a Biology Bay strewn with collapsed benches, broken equipment and the motionless body of a man, twisted into an agonised rictus. A silence broken only by the Doctor's hissing intake of breath, that existed for all of a second.

'Who is it?' asked a scared voice.

'I can't tell,' quietly replied the Doctor. 'His face has gone.'

True enough, the boilersuited body had a giant mass of slimy green tendrils knotted in a collation where a head ought to be, both hands buried white-knuckle deep in the twisted masque. One or two tendrils twitched spasmodically, a chlorophyll frenzy that made onlookers flinch.

A chorus of startled cursing and surprise greeted this description of the body, ended by a piercing shriek as Delgerdzaya pushed her way to the front of the group, saw the body and collapsed.

'What the hell is going on!' shouted an onlooker.

The Doctor knelt over the body, felt for a pulse and didn't find any. He looked up in time to see Roj push between the rapidly-growing crowd.

'What did I tell you about solo research?' snapped the Time Lord, fixing Roj with a stare so bleak it might have sterilised medical instruments. The unmentioned Rutan threat hung on his words, if only to those who knew of that very same threat.

'Eh? What?' blustered Roj.

His reply was ignored by the Doctor, who now paid much closer attention to the corpse in front of him. Green and yellow sap oozed from beneath the knotted green tentacles, pooling underneath where Mike's head would have been under normal circumstances. The pallid fingers, dug deep into the green mask, were absolutely rigid, saps leaking from where they had penetrated the vegetable matter.

'Play back the wall camera,' suggested a voice from the watchers. 'That records what people in here do.'

- an introversion. Literally. Cholon must have been attacked by the flora he was examining and asphyxiated when he couldn't release himself from the -

'Doctor?' asked Rose, leaning over him, noticing the glazed look in his eyes. 'We're going to play back the post mortem camera.'

'Oh – right. The camera.'

The fateful scene where Mike agreed to speed up his examination played, followed by his placing the Kink Bush, set firmly in it's hydroponic holder, into the Hard Radiation Chamber. He took refuge behind a second lead screen, used the remote to bombard the plant with x-rays long enough to develop an exposure, then waited until the Chamber door unlatched after the default safety period. Mike carried the Kink Bush out and placed it onto a bench, noticed unusual activity and returned with a heavy-duty scalpel, scoring into one of the normally inert seed pods.

With a speed and suddenness that made people jump, the pod erupted outwards in a mass of green tentacles, wrapping itself firmly around the nearest object – Mike's face. The Mongolian jumped backwards, trying to pull the writhing green mass free with frantic tugging, failing, falling and crashing into the Bay's benches, lurching and eventually collapsing, his fingers plunged into the still-thrashing green tentacles. Gradually the plant stopped moving. Within seconds, the Doctor could be seen to arrive on the scene, ahead of a mob of mission personnel.

'Why did you allow that!' asked the Doctor, looking at Roj coldly.

'That wasn't me!' replied Roj, heatedly.

'Strange, because it looked exactly like you,'broke in another voice: Kendal Kellerman. 'Makes me wonder why you deny being here. Knew what was going to happen, did you?'

'How dare you!' snarled Roj, the pent-up anger about everything that had spiralled out of control boiling over. He seemed about to lay into Kendal with both fists until the Lowry tech produced an induction pistol. People hastily backed away on either side.

'Uh-uh. Since you, Mission Leader, are implicated in the death of the Mission's Second in Command, and the Third is that ineffectual buffoon Chadwick, I'm appointing myself Leader.'

Rose had discreetly sidled over to a bench that held various plastic bottles of different chemicals, hoping to find one that would prove effective in either smashing over Kendall's hateful bald head or having it's contents thrown over his face. She saw the technician's face flush with anger at an event hidden from her viewpoint by an overturned bench.

'Get away from him! Vermin!' followed by a loud whizzing noise as he levelled the induction pistol and fired. A brief high-pitched animal squeal echoed around the chamber as the round hit home, and a TESTer pitched dead over and over, ending up against the far wall. Another darted away, running in a frantic zig-zag towards the exit doors. It wouldn't have made the doors had Rose not hefted and thrown a nearly full bottle of "Anionic Buffer" at Kendall, hitting him on the temple and forcing him to hold fire or kill mission staff. He turned back to level the pistol at her midriff.

'Yes, go ahead and shoot, you sadistic bully!' she blurted, not sure quite where the words were coming from. 'I don't like them but they don't deserve your treatment!'

Kendall rubbed at the large dint in his temple, careful to keep his attention divided between Rose and her companion.

'I might have expected rubbish like that from you.' He raised his voice. 'All this trouble started once you and Doctor Smith turned up. "Rebel colonists" be fnorped!' in a tone that made it clear he had been the one trying to shoot Rose or the Doctor. He pointed at Arpad. 'Get three plastic tourniquets for this lot. They get locked up until I get proper answers.'

Matters might not have further deteriorated had not Delgerdzaya been responsible for applying the tourniquet to the Doctor's wrists. She had recovered from her swoon and now acted with a blank desperation, belied by her concentration on applying the plastic restraint loosely enough.

'Is that alright – not – not – what - ' she began and stumbled. Kendall noticed immediately.

'What's up? You alerady knew neither of these two supposed rebels have their tattoos didn't you?'

Delgerdzaya was testing the Doctor's wrist, looking more and more alarmed. She reached for his neck and he tried to twist away, until Kendall levelled the induction pistol again and shook his head menacingly. Delgerdzaya eventually got a stethoscope and checked the Doctor's chest, with mingled wonder and alarm.

'What!' barked Kendall, animated interest all over his face.

Oh no! realised Rose. Double-heartbeat. She wished that bottle had been full of fuming nitric acid and broke on impact.

'This man – well, he's not a man. He has two hearts. Two hearts. Two,' stammered the biologist. 'He's an alien.'

The Doctor pulled a rueful face and tried to smile.

'Technically, I never claimed to be human. Just to be fantastic. Near perfect.'

Kendall sneered and levelled the pistol.

NINE

Nils Gundarsson took Kendall's seizure of leadership with a touch of fatalism. Nils had reluctantly signed on for this mission, one where the local sun might go supernova at any moment, in order to quash his and his wife's failure to apply for a Pregnancy Approval Warrrant. Kristen getting pregnant wasn't part of their plans, rather a faulty batch of contraceptive was. That faulty pharmaceutical meant they got the option of volunteering instead of an eight month sentence in a Det Camp, with automatic PAW for the next decade when their contract was completed.

Out here he was under-employed. Six feet two and nineteen stone, he'd been assigned to the Humpers and Dumpers under Kellerman where brute strength and size would matter. Except that the discovery and clearance of Serendipity bunker meant little construction work. His specialism constituted translation of the Icelandic eddas and sagas from dialect into formal English; Kristen was a comparative philologist who studied Scandinavian, Anglo-Saxon and Germanic languages. She was underemployed, too, both back on Earth and here on ZLM Prime. Not that being under-employed was such a bad thing, since Kellerman constituted a complete plabby and the less contact one endured with him, the better one felt.

Kristen came back into their cubicle, pushing a trolley piled high with an amazing collection of electronic junk.

'Those two strangers and Roj have just been marched into the CCD tent. Kellerman's like a dog with - '

'Good!' muttered Nils, considering Roj to be little more than a glorified spy working for The Administration. 'What's all this rubbish!' he continued, rubbing his spiky blond hair backwards with one hand whilst pointing at the trolley with the other. There was little room already in the cubicle without importing trolleyful's of junk.

'It's not rubbish. That Doctor Smith built it to play the recordings our alien predecessors created.'

That bald statement left Nils at a loss for words.

'Well, he can't play any of it now. Like I said, he's under guard in the CCD tent. The only place that can be sealed from outside and without any privacy.'

'What are you going to do with it?'

' "We", dear husband! We, using our combined talents and experience, are going to analyse the alien recordings.'

Nils rubbed his hair again.

'An unknown alien language? You're being optimistic!'

His wife's eyes had a wicked twinkle in them.

'I've already played a couple of these recordings. We have an alien script, and their spoken language, and reference to lots of things on the filmed record.'

Looking up and to the right, Nils contemplated the possible juxtapositions and matches –

'Hey!' he complained. 'You snuck that one up on me! Intellectual ambusher.'

Kristen held up a tiny crystal.

'Stor eggen, ud lille agern,' she smiled.

'Oaks and acorns; what are you, a botanist?' grumbled her husband, grabbing a notebook.

The Doctor looked out at Serendipity via the obscuring plastic screen of the CCD tent, pursing his lips in a self-satisfied manner, even managing to hum a tune.

'Dunno why you look so happy,' complained Rose. 'I feel like the filling in a glass sandwich.'

He glanced back for a moment.

'Think about it, Rose. Kendall could have decided to test for extra-terrestrials amongst the mission. Aliens. That would have panicked our infiltrator.'

With an expansive and non-judgemental gesture, the Doctor indicated Roj.

'Whom implicated and coerced Cholon into his woefully dangerous research.'

The Mission leader abruptly came to, from his wilful neglect of events and personalities.

'Eh? What was that? It wasn't me in that film!'

The Doctor levelled a look that would have either boiled tarmac or chilled wine.

'Of course it wasn't. Both of you have no doubt realised that the "Roj" in the video wasn't actually Roj.'

Obvious, really, to anyone who could think themselves into the mindset of an alien.

'It was the Rutan, trying it on?' answered Rose.

'Yes. You'll notice that "Roj" didn't actually speak. I don't think our little mimic has been able to study him enough to get the voice right.'

Rose looked at the mission leader in calculating fashion, sufficiently enough for Roj to feel uncomfortable and unhappy. Not only did his wife dislike this attractive young Freethie, he was locked up in close proximity with her. And her Radic alien boyfriend!

'Hey, hey, just a minute, let's not forget who's the problem here! I'm human. You're not.'

The Doctor looked at Roj with a certain degree of astonishment.

'In my part of the galaxy, Mister Taylor, you would be the alien. You, not me. Let's not fall into the folie a deux of xenophobism, hmmm?'

Roj backed off in alarm, only for the stranger to back off with equal wariness. In fact the Doctor lurked in a corner of the giant plastic bubble from that moment onwards, leaving Roj and Rose to their own devices.

'Is he really an alien?' asked Roj. 'I mean. He looks really human.'

That earned him a gigawatt glare from the young woman.

'He's more human than most of your mission!'

Alone in his acutely-angled corner of their polyvinyl prison, the Doctor cast his mind back over recent events. Murder, sabotage, aliens, an unstable sun, the Grey Empire, spies, traitors – what else could be added to the mix?

Dead aliens.

Extinct dead aliens, for one thing.

Extinct dead aliens seeking a big killing, a major result from the research conducted here.

- and a sudden, relevant aspect of what he'd witnessed so far jumped precipitously into his consciousness.

'Eureka!' he whispered. Everything fell into place. He played it backwards and forwards mentally, just to make sure. The revelation that he wasn't human might also have a bearing, if that wasn't cancelled out by his genuinely concerned attitude and behaviour.

Which might have been relevant or useful if a parade of humans hadn't marched along the bunker floor outside, parallel to his cell. None of them were friendly, a couple were armed, and they all seemed intent on inflicting harm upon either himself or Rose. Kendal Kellerman stood at their head.

'What have you done with it!' he yelled the instant he walked into the CCD chamber, the words falling flat and lifeless thanks to the anechoics.

'What!' gasped Roj. 'Done with what?'

A clutch of worried staff had come along with Kendall, pausing to look into the CCD chamber interior.

'Cholon's body! It's gone!' snarled Kendall, looking like a dog about to bite.

The Doctor whirled around from his intellectual reverie, horrified at what he'd heard, without really understanding why.

Kellerman still wielded his induction pistol, and it's muzzle followed his eyes as he glared at each prisoner in turn.

'I know you've got something to do with this. I know it!'

'How?' asked an exasperated Rose. 'We were locked in. You know, unable to get out. Locked in.'

'When did it go missing ?' barked the Doctor, to a sneer from Kellerman. The technician stood back outside the chamber and looked around the staff, his eyes settling on Davinia, Montag's wife.

'Tell me when!' asked the Doctor again.

'Davinia. Execute Programmed Over-ride Trilby,' he hissed, and grinned maliciously as the woman's expression went blank. He grasped her right hand and put the induction pistol into it.

'Stay on guard here. Kill anyone who tries to get in, and kill anyone who tries to get out,' ordered Kellerman. Davinia mindlessly droned the order back in repetition, standing rigidly in front of the chamber door as Kellerman swung it shut. He mouthed a last sentence at the prisoners, none of which they understood.

The Doctor braced himself against the transparent wall of the chamber, gritting his teeth in anger. Rose stared at the expressionless Davinia, standing with all the poise of a statue. Roj stared at his knees, utterly lost.

'What's up with her?' asked Rose, turning back to face the Time Lord.

Instead of answering, the Doctor slammed a fist against the thick plastic, making the chamber shudder. He turned and violently kicked an instrument bench over, sending a cascade of CCD's to the floor.

'I know it all now, the whole lot,' he snapped, glaring at the frightened Roj. 'Everything. I just have to work out if you knew it, too.'

The implication that if Roj knew what "it" was, that if he knew and concealed that fact, the implication was that he would suffer severely.

'Doctor!' asked Rose, louder this time. 'Davinia? What happened to her? Did that little weasel hypnotise her?'

As if slapped, he turned to face her.

'What? Hypnotise? Him!' and he made a dismissive face, trying to disguise his underlying dislike, distaste and disgust. 'No. Davinia was processed back on Earth. Given a comprehensive course of drugs and brainwashing and hypnosis and who knows what else, in order to be the secret assistant for this mission's internal spy. If he speaks her codephrase, she turns into an obedient robot.'

Not to mention her inevitable collapse into psychosis thanks to the brutal mental processing.

Roj began to pay attention.

'Kellerman? Kellerman is that spy you mentioned?'

'Bravo!' applauded the Doctor, sarcasm dripping from every syllable. 'However, can you focus on the bigger picture?'

He stopped talking, reflecting on a story eight hundred and fifty years in the making, with a background history one hundred and twenty five thousand years in the making.

Rose divided her attention between Davinia the statue and the Doctor, who seemed irate at Roj - when the mission leader exhibited all the backbone of a jellyfish.

'What's the bigger picture, Doctor?' she pleaded.

He stared, gimlet-eyed, at Roj, who positively quivered.

'Roj, do you really think The Administration would bother to infiltrate a spy into your pathetic little mission! Backed up by a covert robotised slave? All that for forty expendable scientists stranded eight hundred light years from home? Well - do you!'

The mission leader squeaked an inaudible reply. Softening slightly, the Doctor leaned closer.

'Roj, tell me why the Trinarians came here.'

Another inaudible squeak.

Rose took charge.

'Doctor, you're scaring him!' she scolded, then rested a reassuring hand on the frightened man's shoulder. 'Roj, calm down. I know - ' she glanced at her companion ' – I know the Doctor can be a bit scary, a bit worrying, but he means well, honestly he does. Can you tell us why those big reptilianoids came here?'

The Doctor bit his cheek to avoid laughing.

' "Reptilianoids"?' queried Roj. 'You mean the – the Trinarians?'

'Er – yes, them,' confirmed Rose. 'Trinarians. Why did they come here?'

Roj waved a hand, still worried about the Doctor and that gimlet gaze.

'Same reason we did, to study ZLM.'

'A star utterly unique in all the explored galaxy, correct? A periodic variable that doesn't fall into the usual classifications of Cepheid or radial pulsators?'

A silent nod from Roj.

'The Trinarians didn't send a scientific mission, Roj, they sent a military one. They didn't come to study ZLM – they came to destroy it.'

Both Rose and Roj looked at the Time Lord with equal astonishment.

'That's impossible!' complained Roj. 'The energy alone needed - '

'Provided by the fusion plant that sat on the floor below this. A power plant big as Wembley Stadium, working over months, projecting energy via that parabolic emitter witnessed on the crystal record. Oh, ZLM might have been a periodic before they arrived, but their mission was to completely destabilise it. To create an artificial supernova.'

More stares.

'Why?' asked Rose, simply.

'That ties in with the reptilianoid's origins, why they came here and why nobody has encountered them since. I ought to be grateful to Kellerman, giving me the chance to sit and think in isolation.'

Rose gestured.

'Don't keep us in suspense!'

'Okay. You've met the Rutans before, haven't you? No? Oops! Sorry, wrong companion. Just so you know, they and the Sontarans have been going at each other, hammer and tongs, for over a hundred centuries. Between them, they've despoiled whole solar systems, killed hundreds of billions and there's still no end in sight.'

He adjusted his pose, going for a more dramatic stance.

'I believe we're looking at an alien race caught in the interstellar crossfire. A race desperate enough to make a last ditch effort to protect themselves. They located an unstable star, ZLM, and intended to use it as a test-bed for their destabilising technology. Quite a deterrent, being able to blow up suns at will. That'll keep the wolf from your door, and the Sontaran from your solar system.'

'They didn't make it back home,' added Rose, sombrely.

'No, they didn't,' agreed her companion. 'Not only that, no rescue ship ever came to find them, or their emergency shuttle, or their – well. Yes. I think they were the last survivors of their race, that their homeworld was over-run or eradicated entirely while they were gone.'

A few nightmare images flickered across the Doctor's consciousness: planets bombarded into radioactive ash, a population enslaved into mindlessness, a culture and race exterminated into anonymous obscurity. The only remnants of the Trinarians were a cemetery on Elysium and an appropriated bunker on ZLM Prime. Not much to show for half a billion years of evolution.

'Not much to show for their life history, is it?' he said, as barbed and acid a comment as he'd ever made.

Sitting and looking intently at the lines on his palms, Roj went back over what the strange stranger had said. Aliens here to blow up the sun. Aliens wiped out by other aliens – the Blobs and the Bucketheads of legend. Aliens running away in order to die on a barren satellite; shape-shifting alien intruders who murdered their way into the mission; secret hidden chambers full of sacrificial aliens. Hidden human spies within the mission. Hidden human killers trying to assassinate other humans –

'I give up. I give up. I'm an astronomer. I deal with astronomy, not spies and murder and aliens and suns blown up artificially.'

'I think someone just resigned,' whispered Rose to the Doctor, who gave a big cheery smile and a warning shake of the hands. Rose turned to see two mission members outside being warned-off by the unwavering induction pistol of Davinia; a big, broad-shouldered, blonde haired man and a woman with cheekbones sharp enough to shave with.

'Rose, I want you to crack that door open when I tap your shoulder,' murmured the Doctor. 'Yes, yes, I know Davinia might shoot me, but I won't be trying to leave, so she may not. Get ready to catch her.'

Not very reassuring! thought Rose. "might" and "may", not good. She felt a light touch on her shoulder and pulled the chamber door inwards. Davinia turned around, minus proper body language, and pointed the pistol.

'Hello there!' began the Doctor, in a voice soothing as honey. 'Hello there - '

Davinia swam upwards.

It was chilly down at the bottom of the – lake? pond? pool? Chilly and the water felt sluggish and turgid. Gradually, as she forced her way upwards, she felt the process become easier, as if hands were pulling on her, helping and hauling upwards.

Daylight beckoned ahead, rippling and warm and welcoming, away from the dark and frozen depths she'd been trapped in. Trapped. She must have been trapped, it didn't make sense to stay down there.

Now that she was closer to the surface, voices penetrated. Hard to make out at first, they became more audible as she swam harder and harder.

'this way Davinia this way' they chorused. 'This way to the light' they continued. 'nearly there nearly there, and now - '

'Awaken!' called the Doctor, in a voice of incredible clarity. The zombie-like posture and behaviour of the woman in front of him ended instantly.

'What - ' she began and ended, dropping the induction pistol to the floor without a second thought, clutching her head with both hands. Ready thanks to a warning, Rose darted forward and caught the woman before she collapsed.

Beyond them, the blond man and woman stared in amazement and worry.

'He just looked at her,' whispered the man.

'Alien, you see,' filled in the woman. 'Mind control powers.' She nodded to herself with assurance.

'And what do you want?' asked the Doctor in a polite conversational tone. 'It has to be important to risk getting shot by a robotised guard.'

The woman darted a look at the man before replying.

'We're language specialists, Doctor Smith.' She drew breath, only to be pre-empted.

'Ah, you've translated the Trinarian records? Jolly good! Let's hear it!'

Nils blinked rapidly in surprise that the stranger had flown to the correct conclusion so quickly.

'Not all of them, Doctor Smith. In fact only a few phrases. These aliens, the Trinarians, they feared attack by an enemy they call "The Converted".'

That had been fairly easy, since the alien commentary had overlaid pictures of that smoking pile of ash in the later recording.

Converted? postulated the Doctor to himself, playing solo devil's advocate.

A religious schism, he replied.

Where nothing previously recorded indicates any spirituality on the part of the Trinarians. No religious beliefs at all.

Political, then.

Hardly! A desperate mission like this would have been extensively assessed before departing, and anyone dubious wouldn't have got here.

'It's not quite so clear-cut as that,' ventured Kirsten. ' "The Converts" and "Converted Ones" also feature.'

Rose helped a shuddering and groaning Davinia to sit on a plastic stool.

'What you need is a cuppa,' declared the young woman. 'Roj! Go and get a cup of tea. Yes now!'

She put her arm around the older woman's quivering shoulder.

'What – how did I get here?' asked Davinia, her accent thicker than normal.

'You were hypnotised by Kellerman,' said Rose, editing the truth a little. 'To help him. He's that internal spy the Doctor warned Roj about.'

Davinia groaned again and clutched her head. Roj, returning with a cup of tea, was followed very closely by Montag, who looked angry enough to rip out Kellerman's throat with his bare teeth. Rose considered this quite understandable, if his wife had been processed into robotic imbecility.

She witnessed the Doctor, conversing with those Scandinavian models, pause and notice Montag. He stopped and came over, chatting so quietly with the German that she couldn't hear him. Montag looked slightly less furious after that.

Davinia, meanwhile, ran throught a whole slew of muttered German words interspersed with "Kellerman", said with venom.

'He must have used me as a guard, a sentry, whenever our rota paired us up,' she hissed. 'I can't remember what I did during, but the before and after is coming back.'

Rose, naturally and intuitively, wondered what Kellerman had been doing that required an armed guard. Before she could ask the Doctor, he shooed the blond Scandinavians away, pushed Montag out of the chamber and dragged Davinia to the door, whispering to her again whilst removing the cup of tea from her grasp. Mystified, Rose looked on as the woman took on her previous pose of immobile vacuity.

These actions were explained by the re-appearance of Kellerman, wielding another induction pistol and just as angry as the last time he'd stormed into the chamber. This time he was trailed by several other expedition members, all looking either angry or scared.

'I'll teach you, you plabby alien saboteur!' snarled Kellerman as he unlocked and yanked the chamber door open, only to freeze in shock as the muzzle of Davinia's induction pistol was pressed hard against the back of his head.

'Just give me an excuse,' she hissed.

'Nicely done!' congratulated the Doctor, twisting the big, ugly weapon out of Kellerman's hand. 'Now, kindly shut Mister Kellerman up in the CCD chamber and we'll get on with the mystery of the walking corpse.'

The hangers-on who'd come with Kellerman all looked unhappy as the technician was pushed, very forcefully, into the chamber by Montag.

'What does the post-mortem camera show?' snapped the Doctor, trying to attain the initiative straight away.

Nobody answered at first. Slowly, other members of the expedition, aware that the worrying armed sentry had gone, began to approach the incipient argument.

'Why should we tell you? You're an alien,' stated one member. Their tone was defiant.

'You should tell me because I'm trying to help you!' stated the Doctor, simply.

'I'm human, and I trust the Doctor,' blurted Rose.

'You should tell him because I've got a gun,' said Montag, careful not to point the induction pistol at anyone.

'So have I!' added his wife, angrily.

Which is one gun too many, realised Rose. Where did that come from? Kellerman! Undoubtedly.

'Come with me,' she whispered to Davinia, then caught the nearest TEST rat. 'Take us to Kellerman's cubicle,' she demanded, and was led there promptly.

Rose looked around the cubicle, strewn with discarded rubbish, in wild abandon.

'Typical man!' she complained.

'What are we here for?' asked Davinia. 'To smash his kit up?'

'No!' retorted Rose. 'Where did you get that gun? Or, rather, where did Kellerman get it? Because there's only supposed to be one of them. One is Mike's, and the other, I bet, is Kellerman's.'

Davinia looked at the gun as if it would twist in her hands and bite. She tucked it carefully into her boilersuit pocket, then started to look around the cubicle. Discarded beer bottles clinked on the bed when Rose moved it. She sniffed dismissively at the empties.

'Yes, he brought a still from Earth in his personal effects. Drunken mooj!' said Davinia, kicking a pile of dirty underwear and boilersuit liners. 'My husband brought the works of Goethe on microdisk, and this plabby - '

Triumphantly, she produced a small, cylindrical metal tank, with the words "kendals still" scrawled across it.

'See! See what I mean!'

Rose sucked in her lower lip.

'I see what you see. Or what you're supposed to see.'

'Shall I play it again?' asked Montag.

'Yes. Slowly, this time.'

Once again the trusty post-mortem camera was rewound and replayed for the audience, now much larger than the handful outside the CCD chamber.

Mike's body, with the hideous, un-natural attachment on his head, lay stark and cold on the lab table. Then, slowly, the green tentacles that marked what had been his face began to stir, twitchily and erratically at first. Rippling patterns of movement then ran across the whole green mass, until it writhed like a ball of snakes.

Almost as if rheumatic, the corpse sat up, swaying. It lurched to one side, then back again. Green be-tentacled head rippling and dancing, the body dragged one leg over the edge of the table, then the other. With an effort, it stood upright, sagging at the knees. Painfully, awkwardly and yet with increasing ability, the body began to stagger around the room. Within minutes the horrid conglomerate organism had begun to walk nearly properly. Abruptly, it left the room.

A chorus of horrified remarks followed these incredible scenes from the camera, none more horrified than the Doctor's.

Looking noticeably queasy, Montag cleared his throat and looked at the Time Lord.

'So he wasn't dead after all?'

The Doctor fixed him with a look of steely intensity.

'Oh, sorry, Montag, but he was dead hours ago. He was dead. That damn plant was only dormant!'

A stunned silence fell in the lab.

'Obviously the irradiation produced an abrupt metamorphosis in the plant,' mused the Doctor, before realising the implications of that sentence and looking up in marked anxiety. 'Oh no …,' he whispered, voice trailing off into silence.

TEN

Being led to the Biology Bay by a TEST rat, Rose and Davinia found the Doctor amidst a crowd stunned into silence by the sight of the post-mortem camera.

'Bad news?' asked the young woman.

'Uhuh,' replied the Doctor, preoccupied.

'What are you carrying Kellerman's still for?' Montag asked her.

In reply, Rose offered the Doctor a bottle, dregs of beer swilling around at the bottom .

'Go on, sniff it,' she told him.

'Lager?' guessed the Time Lord.

'Wrong!' chirped Rose.

Cocking an eyebrow, the Doctor took a sip.

'Coloured water!' he stated. 'Ohhhh, clever, clever - with an additive to make it smell like beer.'

Confusion ran across the faces of the audience who caught this exchange.

Rose cocked a thumb at Davinia.

'None of this lot know anything about alcohol, Doctor, but my dad used to make homebrew and he made it in a bucket. You don't need a still for making beer.'

She held out the small metal cylinder.

'Interesting,' murmured the Doctor, turning it around. He abruptly twisted the base, which unscrewed. Inside was a foam insert. When extracted and opened it had a cut-out in the shape of an induction pistol, with two clips of slugs still embedded in the foam. Another cut out was merely an empty rectangular space.

'Clever girl!' praised the Doctor, with a fierce grin. Arpad leaned over his shoulder and glanced back and forward between the lanky stranger and Rose.

'Er – why fake having beer?'

The Doctor didn't bother replying. Kellerman had been giving the impression he was a stupid, boorish, drunken lout. Clearly he wasn't - it was easy enough for a clever person to pretend to be stupid, rather than the other way round. What else might he be concealing? And what else had he kept hidden in his "still"?

'I need to make an announcement to the whole team simultaneously,' he told Roj, who looked back with resignation and a shrug, barely acknowledging anyone.

The Doctor sighed. Very well, Roj had given up. By default he needed to take charge.

'Very well, I'll tie in and broadcast from the Lowry shack. That'll work. Rose, could you keep looking for whatever else Kellerman hid in that fake still?'

Arpad and Montag came along with the Doctor, which proved lucky in terms of an alibi.

The Doctor could tell that the background count had increased, due to his Gallifreyan constitution. Both men remarked about the increased heat, Arpad shading his eyes to look back at ZLM, which seemed to wobble in the air, an air that visibly baked.

'Let's not tarry,' said the Doctor. 'The UV is climbing, and so is the gamma.'

They plodded over the plastic-covered earth, which reeked of warm polythene.

'That's not good,' observed Montag, seeing the door to the shack swinging open.

"Not good" understated things enormously. The shack's interior was a midden of smashed and broken equipment. Arpad looked dismayed, Montag annoyed.

'I don't know what imbecile did this! All it does is make work for us.'

'You've got spare parts?' asked the Doctor.

Montag nodded dolefully.

'Everything is triplicated. We can build another two shacks out of the stores if need be.'

Another baking slog across the plastic-coating quickly refuted Montag, who delved amongst the labelled and organised storage boxes of Bay 1, becoming ever-more anxious and drawn. Murray McIlwain, in charge of stores, came over to ask what was missing.

'The core tubes for the Lowry!' snapped an angry Montag. Murray picked up the two empty metre-long opaque plastic boxes that lay on a shelf, looking into them with a stupid expression.

'They were here. I inventoried this lot a week ago.'

'They're not here now!' barked Montag, wiping his brow.

'Check all these boxes,' ordered the Doctor. 'All of them. Find those tubes!' and such was his tone of command that neither Montag nor Murray stopped to quibble. 'Arpad – give me your wrist-phone. These things don't have a conference-call function, do they?'

A mute shake of head from Arpad.

The Doctor took the proferred wrist-phone, wielded his sonic screwdriver and opened up the comm device; he wrinkled his nose at the circuitry, pulled a few connections loose, altered more with the sonic screwdriver and held it to his mouth.

'Testing, testing, hello Filmore West,' he announced. The same words came booming out from Montag and Murray's wrist-phones. 'This is Doctor Smith. Please pay very close attention to what I am about to say. Your mission has been infiltrated by a Rutan. For those of you who aren't familiar with Rutans, they are shapechangers, and one mission member is not whom they appear to be.'

He paused to let this sink in, and to judge from Murray's astonished expression, the pause was necessary.

'From now on avoid being on your own in isolation. Prefereably, work in threes. That way we can avoid any more substitutions. Oh – under no circumstances try to detect the Rutan. If threatened, it will kill. Left alone, it will merely continue to observe. If you want more details see Montag, Arpad, Geoffrey or Barry. Don't bother with Roj.'

Whilst the Doctor was informing people of the bad news, Rose and Davinia continued to tidy up Kellerman's untidy cubicle. A pair of TESTers came to gloat at the cubicle entrance, bobbing and hissing to each other in rat language as the two humans cleared the domicile. Dirty cups, plates and disposable cutlery were swept up and dumped in a plastic bag, whilst waste paper lying crumpled up or under the bed got quickly scanned and chucked away, too.

Davinia, of course, was alarmed by the broadcast announcement about an alien spy. She gave Rose a few worried looks, until complacency set in thanks to the dullness of their task.

'Typical!' muttered Rose, removing the dirty pillow from Kellerman's camp-bed and finding a glossy magazine printed on what looked like filmy plastic sheets. 'Perv.'

'What is it?' asked Davinia.

' "Swimsuit catalogue 4212 with holographic inserts",' recited Rose.

Davinia wrinkled her nose.

'If Montag brought home stuff like that - !'

Rose went to chuck the hi-tec magazine, before pausing.

'Course, he'd expect anyone who found it to chuck it. Let's see - ' and she riffled through the pages. Nothing out of place: lots of photos of women in bikinis, no hidden information or pages glued togther or anything lodged in the spine. She nearly skipped the index, before noticing that instead of page numbers, the figures were of percentages. They started at 02.75 and worked their way up to 27.3, after which normal page numbers resumed.

'This is well dodgy,' she stated, sure that she'd uncovered more subterfuge from Kellerman, unsure exactly what it was. 'Any woman who found this thing would bin it or drop it, and any man wouldn't bother looking at the index. Well dodgy!'

That earned her a look from Davinia.

'Is "Welled Odjee" that bad?'

Rose curled her lip.

'Lairy big-time!'

Back in Biology Bay, the Doctor chewed a nail and worried.

The core tubes for the Lowry mechanism couldn't be replaced. Whilst they had enough spare parts to rebuild everything else, or cannibalise other components, or use substitutes, those core tubes were vital; vital, unique and – gone.

Nils and his wife were back in their cubicle trying to translate and transliterate the Trinarian crytals, seeking more information. Kellerman remained locked in the CCD chamber, yelling at anyone walking past. Roj sat staring into space – having apparently bowed out of reality. Mike's body had vanished, leaving the Doctor with an unpleasant supposition about why.

A tap on his shoulder brought the Time Lord back to the present.

'Hello Rose. What's that – a catalogue of swimwear?'

'One with a dodgy index. Look – all in percentages instead of numbers. What d'you think of that, eh?'

'Hmm. An idea suggests itself. You didn't find whatever else got hidden in that fake still? Oh well, too much to hope for that, I suppose.'

'Do you know what it is?' asked an utterly baffled Davinia.

'I'm pretty sure,' replied the Doctor in a nonchalant way. 'Right now it's not our most pressing problem.'

He began to take mental stock of where the expedition stood, before another tap on the shoulder.

'Oh. Christy. Come to collect Roj?' he blurted, a little sharply.

Roj's wife narrowed her eyes, causing the Doctor to remember certain Italianate Renaissance aphorisms about scorned females.

'I've come to tell you about the radiation!'

'Er – yes?'

'We have an escalation of infra-red and ultra-violet wavelengths, X rays and gamma rays, into the second percentile. For the meantime travel outside is alright. In a few hours, a day at most, travelling outside will roast you like a chicken!'

For you, perhaps - began the Doctor, before recalling himself.

'Oh – oh, that's awful. Very bad indeed. Terrible,' he ventured. Christy glowered back at him.

'Ha ha, very funny, I hope aliens understand sarcasm.'

With a scathing glare at Rose, Christy stalked off to sit next to her husband, whispering into his inattentive ear.

'How terrible is it, really?' asked Rose, looking at the catatonic mission leader and his fussing wife.

The Doctor looked back at her with a touch of disbelief.

'Rose! This mission is stranded on an alien world eight hundred light years from home. They have no way to communicate with Earth. The mission has been infiltrated by an alien killer, who has already murdered one person. The local sun is radiating enough energy to shortly kill anyone out in the open. A mission member has been killed by a local plant. I don't think anything else need be added to make things worse.'

The young woman shrugged, opening her mouth to retort with a quip.

'I'm an astronomer, not a spy or a soldier,' interrupted the hollow tones of Roj. Both Rose and the Doctor were taken aback, as were other people checking out the remain of Mike's Kink Bush. 'An astronomer.'

'Of course you are,' murmured Rose, rolling her eyes. She got a tut-tut look from the Doctor.

'I've been going over the activity of ZLM mentally. While you lot were running around playing the action heroes, I've been calculating.'

The dozen people in Biology Bay stood still, listening carefully. Roj lumbered to his feet, Christy at his side. The erstwhile mission leader pointed at the Doctor.

'This sun has been destabilised deliberately. It's behaviour is not normal. We cannot use the Hertzsprung-Russel or the Oeming classifications for it, because it's unique, and hence unclassifiable. I've been modelling four-dimensional emission scenarios for ZLM for hours and there's a worrying possibility.'

As if to create an added air of drama, Roj paused and licked his lips. Rose found herself leaning forward, willing him to continue.

'This sun's instability is a non-linear catastrophic accretion model. Utterly different from any observed solar activity in the past.'

The Doctor, alone of those listening, felt a chill travel from his neck down to his coccyx. Rose tilted her head to look at him.

'Translated into speech comprehensible to everyone, Roj means that ZLM's instability may continue to increase, instead of dying down. We don't have two hundred years.'

'We may not have two hundred hours,' agreed Roj. 'ZLM could go supernova in five minutes.'

Exchanging worried glances, people began to talk.

'Roj,' began the Doctor, putting a fatherly arm around the larger man. 'Didn't The Administration give you any lessons in man-management?'

After hearing the broadcast warning from the Doctor about an alien infiltrator, Nils stared at his wife worriedly. She continued to map possible congruencies between recorded images and the alien chatter also carried on the crystals. They had already managed to elide "The Converted Ones" from the records, which had been fairly easy.

Kirsten gradually realised what the broadcast had said, and the compelling tone it conveyed. She looked at Nils, who returned her gaze.

'Yes?' she snapped, after a long, wordless silence.

'Oh, nothing,' replied Nils, happy that only his wife could manage quite that snappish irritation.

He went back to looking at the alien language, with it's big, looping cursive script. Okay, they had the concept of Converted plotted. Initially he'd considered that the term "converted" applied to a religious or political schism amongst the aliens – mirroring the Doctor's thoughts almost exactly – but hearing about the Rutan changed his mind. Okay, if that was the case then there would be adjectives and nouns dealing with substitution, shape-changing, assimilation, copying and sabotage. He ran a long section of scrolling script on the lash-up the Doctor had created, using a thin-film applique reader over the monitor to scavenge the script and capture it to his own computer.

After ten minutes, he got the soft chiming note that meant the alien script had been stored and was ready for analysis. Bringing it up on screen, he began to look for "converted" and any text before or after the target word.

Meanwhile, Kristen was compiling an alphabet-equivalent for the Trinarian script. She had surveyed all of the crystal recordings, and was certain she had all the alien characters recorded – eighty one characters, which happened to be three raised to the fourth power. There were no diacritical notations in the Trinarian writings, nor any variation between lower-case or upper-case denomination, which made things simpler for her. Noun gender – that remained to be seen.

A loud "tut" from her husband drew her attention back to the real world and real time.

'Nils!' she scolded. 'A genuine alien language to work on and you disturb me! If I can translate this - then we can have more than one child! I feel sure!'

Nils looked back at her with frustration evident on his open, unsubtle face.

'Sorry. Sorry, it's just that I keep getting "plant" and "movement" when I translate. I've benchmarked from scratch each time.'

After locating references to The Converted in the scripts, he would have expected to see words more descriptive of a Rutan, of infiltration or shapeshifting or sabotage, instead of botanical references.

'Well take them as correct. See where that gets your translation. Don't interrupt!'

Back she went, to try and match pronunciation to lettering. Nils, meanwhile, patiently worked to crack the alien language, succeeding far too well for his peace of mind, eventually staring with mingled horror and awe at the lettering.

'Kris, we need to go see that Doctor, right now!' he almost shouted at her. Unused to her normally-placid husband getting so anxious, Kristen followed him without a quibble.

Harry Lockwood glanced out at the seething, scarlet sky, where masses of clouds battled each other and thunder echoed distantly. Christy Taylor had fixed a thermometer to the inner wall of the bunker, with a sensor out on the outer skin; currently it read nearly 40 degrees, and a WARNING light had come on under the "X-Ray" button.

Shaking his head at the risks he ran on this peculiar world, Harry went and stolidly began to look for the air-conditioning filters that were his responsibility. They came in a grey cyclindrical wrapper with "fragile" markings, and were stored in big plastic chests filled with expanded polystyrene beads. Delicate and necessary, nobody wanted to breathe roasted air unstrained of dust, most especially now that the external temperature was soaring. Under conditions like this, air-conditioning was vital, not a luxury.

Harry took four of the big cylinders out from their protective chest and made his way across the bunker, intending to take his personal shortcut to the floor below – the cargo lift. His stature was slight enough to permit entry, whereas people like Roj or that big Scandinavian simply couldn't fit. Since using it for personal transport was frowned upon, he timed his entry into the cubicle to coincide with an absence of people, dismissing any risk from what he categorised as "Bloody Alien Wierdoes" that included the peculiar Doctor Smith.

The opaque door of the upper-level entrance gave way to the gloom of the underground level, where the clear plastic lift walls allowed Harry a splendid view of the underlit immensity of the cavern. He debarked solemnly, trotted over to the air-con plant and swapped out the old filters, replacing them with the nice, squeaky-clean new ones. The old, worn ones clanked and rattled on the bunker floor, sending echoes fleeing around the chamber. For a second Harry felt like a small child in a dark bedroom, alone and troubled by noises.

It was undeniably lonely down here, he realised. The background bustle of the first level simply didn't reach to the underlevel. Shrugging his shoulders, Harry stepped back into the lift. Instead of a smooth climb upwards, the chamber juddered and stopped straight short of the upper level.

Muttering a curse, Harry tried the doors, but they had locked. Sighing, he jumped and pushed the service hatch open. He'd need to climb up the inside of the shaft, and open the doors from the inside.

The unappealing gloom of the upper liftshaft seemed to twitch and move in a trick of the light. Harry jumped, caught the edge of the hatch and dragged himself up by main force, balancing in the spaces between the cables.

There! he had seen something moving!

A darker mass against the background of the liftshaft stood up, making an unpleasant sucking sound, leaving a smaller bundle of dark matter lying on the chamber roof. The tall figure moved slowly forward, bringing it into the light cast from the lift chamber below. There was something odd about the head – far too big, and with strange hair that moved –

With a final jump, the figure came face to face with Harry, who drew in his breath for a scream that never came –

The Doctor found his lack of detailed botanical science only a minor hindrance; he was going to learn by doing when it came to the Kink Bush and it's variants.

Firstly, he cut one of the seed pods from the plant that had killed Cholon, now rather battered after being pawed about and treated with suspicion by staff. Taking a powered cutting tool, he split the pod open lengthways, careful to keep it well away from him.

The collection of limp green strands that curled inwards from the walls of the pod lay immobile, not reacting to his poking them with a rod, nor reacting to getting a dilute solution of nitric acid poured over them. They did twitch when he gave them a quick going-over with a Bunsen burner.

'Radiation the key,' he mused aloud. 'I'll need to give this a bit of a blast in the Hard Radiation Chamber.'

'Is that wise?' gasped Arpad. 'That thing killed Mike.'

'I'm being wise after the event,' cautioned the Doctor. He set up the halved seed-pod in the protective chamber, then delivered an exposure of three seconds, about what Cholon had tried. Using lazy-tong clamps, he moved the pod into a metal bowl and carried it into the main lab. Everyone gave him a wide berth.

Without warning, the immobile green strands suddenly erupted outwards, dancing and writhing in the air and causing several onlookers to jump in alarm, including Rose. The Doctor moved the clamps directly over them, watching as the miniature tentacles tracked this movement.

'Motion sensitive,' he muttered, before looking up at worried members of staff. 'Don't worry, it has no inherent ability to move on it's own.'

Motion-sensitive meant that the pod Cholon unwittingly activated went straight for him when he tried to move away. After growing into his nervous system and musculature the parasitical plant had used him to gain mobility and move away.

With a sense of foreboding, the Doctor turned to see Nils and his wife entering the Biology Bay.

'We know what the Converted are, Doctor Smith!' blurted Nils, stopping short at the sign of a mass of green tentacles waving madly from a metal bowl.

'Don't go near it!' warned Rose, feeling faintly ill at the sight of the moving plant. To her, plants had no business moving unless in a high wind!

'We went over the Trinarian records, Doctor, and – well, "The Converted" aren't a religious schism or Rutan spies, they were Trinarians assimilated by ZLM Prime's flora.'

'By plant-life a little like that?' asked the Doctor, pointing at the writhing mass on the table. Nils nodded.

'Turned into walking plants,' agreed Nils. 'Mindlessly hostile and aggressive. They attacked the uninfested Trinarians until destroyed.'

Rose brushed her arms, finding it difficult to avoid retching at this new information provided by Nils.

'I rather suspected it,' sighed the Doctor, leaning forward and clutching the edge of a table with both hands. 'Cholon triggered a process similar to that which affected the Trinarians. His was an accident. I suspect that the Trinarians "infestation" was deliberate.'

Once again Rose shuddered. What an idea! She felt squeamish at the sight of a Venus fly trap in action.

'Listen,' said the Doctor in matey fashion, clutching Nils' shoulder. 'Can you and your wife get back to translating those Trinarian records? Since we have no communication with Earth, your skills are vital. Vital!'

Nils nodded without speaking, slighly non-plussed at the importance the alien placed on the translation skills of himself and his wife.

'Really, vital. Not just now but in the immediate future.'

Casting worried looks over his shoulder at the Doctor, Kristen dragged Nils away.

'Let's see to this chappy,' instructed the Doctor sternly, hefting a fire-extinguisher from the Bay wall, pulling out the safety pin and unleashing an icy blast of CO2 onto the thrashing plant pod. The plant froze solidly, until the Doctor followed up by hitting it with a retort stand, whereupon it broke and shattered apart. Rose carefull swept these bits into a disposable bag, and, directed by the staff, dropped the bag into the rotating molars of the waste disposal unit. The rest of the Kink Bush went down the disposal unit, too.

The Doctor stood back and winked at Rose, trying to divert her attention from playing over what Nils and Kristen had uncovered. He'd suspected some kind of parasitical attack after refuting any other possible explanation for "The Converted", creating a kind of fratricide amongst the aliens. After all, there were only seventy five of them accounted for. Where had the other one hundred and seventy five vanished to?

A TEST rat poked it's head around the inner swing doors of the Biology Bay, scanned the room and left again without speaking or signalling. Abruptly, it bobbed back in again and darted over to Rose, standing on it's rear legs.

"?" it signalled. "14 gone".

'They seem to like you!' remarked Montag.

Rose wrinkled her nose at the stocky man.

'They have good taste,' she riposted. Montag rolled his eyes and shook his head.

The rat tugged gently at Rose's boilersuit leg. It tried to look appealing, but remained firmly rat-like.

'Oh go on,' said Rose, gently exasperated. Montag sighed and followed her as well. The rat led her off and into the depths of the first bunker level, weaving amongst tables and partitions, disturbing the odd person still moving around on a mission.

Their end destination was a chamber attached to the inner wall of the bunker, where double doors and indicator lights showed it to be a lift.

'!' signed TEST rat 3. 'Strange smell' it added.

Rose tried a button to open the doors. They remained shut.

'Lift's stuck in the shaft. Wait a second, I'll get a crowbar,' announced Montag. He vanished, returning with a heavy iron crowbar, and set to on the closed doors. They resisted only for a moment, before slamming open. Montag stumbled backwards at the suddenness of the action, falling on his behind. This saved his life.

Rose went to peer down the now accessible shaft, only to be pre-empted by the frighteningly sudden arrival in the shaft doorway of a figure that leaped from the lower darkness. It perched, balancing, on the ledge for a second, allowing the young woman to get a good look.

What had once been Cholon was now loathsomely different. The mass of green, writhing tentacles in place of a head were now even longer, dribbling sap from their ends. The body's arms had swollen so much that it's boilersuit sleeves had burst, displaying green-tinted arms that bulged and pulsed. Elsewhere, the body seemed bloated, throbbing with an evil rhythm.

Rose backed away, petrified. Sensing motion, the horrid hybrid creature lunged at her.

ELEVEN

With a long zzzzzzip! one of Montag's induction pistol rounds tore into the hybrid creature poised to pounce on Rose. A fist-sized hole, gouting transulcent green fluids, appeared in the creature's chest as the induction slug continued on, whizzing into the bunker's interior and bouncing off the roof with a high-pitched whine.

Rose cowered down, sprayed with the liquid debris from the creature.

'Get a fire extinguisher!' she yelled at Montag, who rolled to one side with commendable speed, looking for an extinguisher.

Recovering it's balance and not seeming bothered by the hole shot in it's middle, the mutilated monster thrashed it's head tentacles and started towards Rose, who crabbed backwards over the bunker floor. She shouted for help, until a solid partition stopped her movement.

The writhing, dripping, soundless monstrosity lowered itself towards her, all the tentacles straining at her, straight and stiff as pokers. Rose prepared to fight them off with her bare hands –

A silent grey blur hit the Cholon-plant hybrid from the front, knocking it backwards, followed by other darting grey attackers that moved in from the sides, TEST rats in full attack mode. They ran in and bit, then retreated, then ran in to bite again, at least a dozen of them. The hybrid creature lashed out, missing any of the deft-footed rodents, who continued to nip and bite and dance about in wary aggression. They tugged it away from Rose, into the open area of the bunkers floor, giving Montag an opportunity.

The stocky German cradled a mini-extinguisher in one hand, the release tag in the other hand. He scooted a long gust of frozen CO2 at Rose's attacker, which jumped backwards, then ran away, lurching and shambling and paretic, but rapid. It outpaced the vengeful rats, and a departing round from Montag merely slapped into it's back with a hateful flat smacking sound.

Rose, Montag and the hissing rats all chased after the dislocated, flailing escapee, barging aside a few scared bunker residents. They continued chasing up the entrance ramp to Serendipity, until stopped by a loud hail from behind them.

'STOP!' barked a loud, familiar voice. Rose turned to see the Doctor conducting an Administration Olympic Hurdle, jumping over desks and chairs and partitions. A small flock of followers tried to imitate his exploits.

'Hold it, Montag,' warned Rose, arms outstretched. 'You lot, too,' she warned the rats. 'And thank you big time,' she added.

"!" signalled 3. 'Rose friend,' it added, to a reluctant roll of the eyes.

Rose eyed the creature with considerably less dislike than she'd felt earlier in this encounter. Yes, they were giant rats. However, they were more intelligent than any other non-human native of Earth she'd come across. Plus, and this was a big plus, they'd helped to prevent her death at the hands of that hideous plant-human hybrid.

Skidding to a halt at the end of his racing pursuit, the Doctor wiped his brow and looked Rose over.

'You okay?' he asked, manifesting a false nonchalance.

'Kinda,' replied Rose, looking sideways at him, and then at the baking landscape outside. 'Montag and the rats helped save me.'

'Yeeeeees,' drawled the Time Lord. 'Sorry I couldn't be there in time. This kinda supports my hypothesis.'

Rose looked outwards, at a landscape that swam and rippled under the excessive heat of ZLM, tinted scarlet, under a sky that fought itself.

'D'you think the radiation will kill it?' she asked.

'Nope. Not at all. It got away, and we can't follow it. Well, you can't,' he added, with a knowing undertone. Radiation didn't bother Gallifreyan's any more than bright sunlight botherered humans.

Montag kept away from the daylight demarcation line further up the bunker's entrance, knowing full well that to venture that far meant being cooked alive from the inside out. The TEST rats meanwhile were scampering back to other tasks in the bunker. He watched them go with a touch of awe.

'You know they saved your life, Rose?' he asked. 'That's the first time I've ever seen them do that.'

The Doctor began to walk away from the bunker entrance, only to stop once he heard Montag's words.

'You're quite correct. I don't think it was all gratefullness to Rose that brought them here. They detected an intruder, a stranger strange beyond any human classification. An intruder that killed one of them.'

Montag brightened.

'Do you think - '

'No!' interjected the Doctor. 'The Rutan will have a hormonally-based scent appliqué that makes it smell human. It's an alien, not an idiot, or your rats would have detected it ages ago.'

They walked back across the bunker floor towards the liftshaft, where staff were shining torches down the shaft and making horrified exclamations. Within half an hour the body of a technician, Harold Lockwood, and TEST rat 14 had been hauled up and deposited onto the floor.

Both bodies were in a dreadful state. Rose glimpsed Lockwood's body and promptly felt sick; the man's head had been mutilated by gaping holes that tunnelled into the cranium, leaking tell-tale green sap.

'Doctor!' she gasped, feeling her stomach flip over once or twice. A strong, paternal arm circled her shoulders, hugging her inwards.

'Not pleasant,' agreed her companion. 'We ought to - '

'No! No, that's not what I meant. That green goo, it was dripping off the Mike-thing before it attacked me.'

The Doctor felt Rose shudder with involuntary horror at what she'd undergone. It was significant. What about it was significant?

Think! he cajoled his mind. Think think think. Think think think –

'Get away from the body!' he shouted, throwing his arms wide to make a

bigger impression. 'TEST rats! Get me the carbine case from beneath Roj's bed!'

The only rat present, number 7, looked at Rose, who nodded enthusiastically.

A scurrying rush of assembled rodents took place, resulting in the case from beneath Roj's bed arriving at the liftshaft within thirty seconds. It was closely followed by Christy Taylor, out of breath and angry.

'I'm going to have you lot turned into snacks!' she shouted. 'That gun's for Roj alone! Who – oh.'

She witnessed the Doctor licking his fingers, then applying clingfilm wrapping to his hand before taking up the carbine. The Firing Ready light beneath the barrel remained green, when by rights it should have remained stubbornly red.

Any protests that might have occurred were abruptly truncated by the body of Harold Lockwood, which suffered further indignity. With a soft but discernible pop, the corpse's head suddenly bulged outwards symmetrically, taking on a green hue. The tips of green tentacles began to emerge from the deep holes within the unfortunate man's head, and his body began to lurch upright.

'Requisat in pacem,' intoned the Doctor, levelling the plasma carbine and firing a single shot.

The headless corpse collapsed onto the bunker floor again, disgusting green goo having been sprayed across the floor, walls and onlookers.

'At least we know that wasn't the Rutan,' remarked one of the staff, perhaps joking with gallows humour, perhaps not.

Holding court in the canteen by standing on a table, the Doctor looked over the assembled mission staff with trepidation. He knew things were far worse than they seemed at present, but stating the full details immediately would quite probably crush everyone's will to resist. Such a collapse would be a catastrophe, and he couldn't count on Roj to play the competent manager role either.

'Okay. Thanks to the output from ZLM, nobody can walk outside at the moment unless wearing one of your two firesuits, which will slow any user to a palsied hobble. The metamorphon that escaped earlier is in no way so constrained, and can walk around under the solar bombardment unbothered.'

Various voices were raised in disagreement or anger, including that of Kellerman, whom the Doctor decided was of more use within the community than outside it.

'I take it you didn't bother to search for the missing body first?' asked the Doctor, looking at Kellerman. 'You just formed a mob. Great. Really sterling stuff. Thanks to you that metamorphon had time to ingest it's host and become seriously mobile.'

Deciding discretion was the better part of getting more criticism, Kellerman remained wisely silent.

'What gives you the right to tell us what to do?' groused anther technician.

'Experience!' barked the Doctor. 'Anyone here encountered a Krinoid?'

A whisper went rustling around the bunker – they'd heard the name, a threat from distant legend.

'Not to blow my trumpet, but I have, and I won each time.'

'What about the Rutan?' asked another voice.

'Safely neutralised whilst we are watching one another,' remarked the Doctor, with a casual firmness that he didn't really feel. Not everyone had come to this meeting-cum-pep talk, so he hoped the missing staff were keeping a paranoid eye on each other.

'When we are able to move around freely on the surface, it's essential that we maintain contact with each other, to avoid becoming victims of the metamorphon. As those who were there saw, it tried to used Technician Lockwood's body to germinate more of it's own kind.'

He looked at Christy Taylor.

'How long until we can move outside without harm?'

She returned his gaze with an equally cool one.

'If ZLM doesn't continue to become unstable and vapourise us all, I anticipate the emission peak will occur in approximately four hours. Permissible safe access to the surface – another twelve hours.'

A chorus of groans and complaints came from the staff sitting huddled on tables or chairs.

'Sixteen hours! What do we do for that long!' complained one of the twins.

'At least all the bugs out there will be killed off,' muttered Graham Chadwick.

The Doctor pointed at him.

'Good try. But wrong. Wrong wrong wrong!' He pointed at the twins. 'And we do a bit more research than you've been bothered to do up to now, concerning this planet's ecosphere.'

He jumped down off the table, certain that he had their attention, and indeed he did.

'You've got sharp ears,' grumbled Graham. Rose nudged him with her elbow.

'You don't know the half of it. At times I think he can read minds.'

Having made himself the centre of attention, the Doctor stood with hands on hips, surveying the assembled staff – about thirty of them.

'What I'd like is two separate teams, one to analyse plants, the other to analyse fauna. Within each team I want half to analyse the specimen's DNA, the other to create a postulate organism, a virtual replicant.'

'We don't have DNA scanning technology,' said an exasperated Arpad. 'Astronomical research, remember? Not biological.'

'I know that and I'll build you a scanner,' said the Doctor emphatically. He felt dubious stares upon him. 'Nothing fancy, and it needn't be too robust or resilient. Shouldn't take long!'

Rose took it upon herself to marshall the crowd into four separate teams and lead them to the Biology Bay. Her rationale was that she didn't have the least bit of scientific training or expertise; she did have a certain cachet as a Rebel Colonist, friend of the alien Doctor John Smith, and a winning smile. So she organised.

Montag found himself held back by the Doctor, who produced Roj's carbine.

'I want you to be sentry at the bunker entrance, just in case that hybrid comes back. If it does, destroy it.' His voice had a harsh and steely tone to it, noticeably different from his normal tone. 'Keep clingfilm on the hand over the firing sensor. Confuses it.'

Montag whistled a TESTer over to keep him company and act as messenger if need be.

Within minutes of waving a temporary goodbye the Doctor was busily ferreting around in the Stores Bay, to the muted horror of Murray McIlwain, who witnessed his precious materiel being inspected, found wanting or cannibalised.

From the wreckage spread in a circle around him, the Doctor held aloft an enormous circular apparatus, the core of which had been a rotary grinder.

'Behold! One high-speed centrifuge.' He glanced at Murray, who seemed to have a hard time believing it. 'Really. The secret's in the frictionless mag-lev bearings I added, you know.' Murray nodded blankly. 'No friction at all.'

From that, the Doctor needed to create a microscope. Not an optical one, an electron microscope. He whistled over a TEST rat.

'Get me a surgical gauntlet.'

He pounced on a set of electronic scales, ripped the back off and began to pry and prod around the interior with his sonic screwdriver, before the TEST rat came back with a surgical gauntlet in it's paws, and a microlens.

'Brilliant!' applauded the Doctor. 'Didn't I say you lot were highly intelligent?'

He set to with furious energy, adding the guts of an electronic sensor probe wired up to the surgical gauntlet's geared-down hypodermic, all broadcasting to a thin-film monitor, with the microlens adjusted over the monitor on a cats-cradle of elastic bands. He sent the rat off to obtain two CCDs, then searched through bins for a micro-worm drive, which he used to arrange the two plate-like devices a few millimetres apart. Another input ran from the worm-drive motor to the rejigged electronic scales.

After a couple of hours, Arpad came to see what progress the unguessable Doctor Smith had made, and got co-opted into carrying an array of improvised electronic gear from Stores to the Biology Bay.

'Got to do this now before it gets connected,' explained the Doctor cheerily. 'It'll be too big to move then.'

Arpad carefully set the enormous centrifuge down in a corner, distant from the teams diligently working away. The Doctor appropriated one of the tables set against the bunker wall to connect all his lashed-together gear, stringing wires and cables around and over and under the various components.

Rose, meanwhile, had used the Doctor's authority to chivvy the four teams into working. Yes, the DNA teams couldn't get to grips on actual DNA until or unless the Doctor got his analyser working – and there were dark looks at that assumption – but she had embarrassed people into starting to talk about the possible implications of the Kink Bush's hideous metamorphosis. Notes were taken, writeups begun and now – here the Doctor was, bearing his incredible forty-second century Heath Robinson equipment.

'Okay!' he announced gleefully, rubbing his hands. 'Open for business. Flora team first.'

Davinia had appointed herself head of that team. There were copious samples of ZLM Prime plantlife cryogenically stored in the next bay, so her assistants had been busy collecting and labelling small cored specimens from there. Dozens of specimen tubes sat in holders, labelled "Kink Bush Variant #3", "Plains Sedge", or "Razortop".

The specimens were emulsified, then placed into tubes in the centrifuge, but Arpad intervened before it got started.

'I want that riveted to the floor, Doctor. It's not safe.' He'd seen accidents with centrifugal equipment where they demolished lab walls after spinning off-balance.

With an enormous rumble, the centrifuge cranked into action and span for minutes. The resulting precipitate was pippetted out and put through electrophoresis, and the samples left from this finally went between the CCD plates.

'No vacuum, but good enough,' muttered the Doctor, peering into the microlens and making interested sounds. He waved Arpad over. The Hungarian looked into the eyepiece and saw strands, recognisable strands.

'You carry on looking,' said the Time Lord, giving the other man a reassuring pat on the back. 'Now – virtual creature feature team. Let's start using your imaginations.'

The scientists, grouped around a bench, regarded him with curiosity. They had set up pocket computers and thin-film monitors along the tabletop and a few were running various programmes.

'I want you people to create a creature that has adapted to regular, immense doses of solar radiation. And I want you to use the specimens collected from ZLM Prime as your models.'

He got stares of varying sorts at that statement.

'In fact, I'd also like you to come up with an ecosystem that has adapted to such solar flare-ups. Not only adapted to, but positively requires the flare-ups.'

The Flora teams got similar requests, using plants instead of fauna. Initially they were incredulous and reluctant, but managed to begin talking, from which ideas sprang freely, leading to computer-modelling sessions and arguments about the viability of proposed organisms. Every half hour a team member would go to retrieve a physical specimen from the storage bay, leading to speculations going off at various tangents.

Rose sat in on the discussions the Fauna team were having while the Doctor patched together bits of his arcane apparatus when sparks flew and it stopped working temporarily.

A couple of the team were as far adrift as she was on biology, whilst others specialised in highly specific areas that weren't applicable to their brief.

'Let's begin with the Faterpillars,' started Graham. 'Are they adapted to a high-background count in terms of hard-radiation?'

He brought up a rotating, semi-opaque hologram of a Faterpillar on his computer, the giant insect-analogue looking like a novelty arrangement of confectionery.

'No. Far too large a surface area, with all those disks arranged along their length,' stated Beatrice, emphatically. 'They would fry like soya-link sausages.'

'Then the Doctor must be wrong about me being wrong,' complained Graham. 'This stellar flare-up will kill them off.'

To Rose, the gigantic creepy-crawly looked –

'It looks like a concertina,' she said, thinking aloud, and then had to explain what a concertina was, complete with imitation playing.

'You rebels have some peculiar fnorping pastimes,' commented Graham, tapping his fingers and staring at the monitor.

Thijs, one of the Littoral Zone 3 biologists present who dealt with neurology, snapped his fingers.

'Brilliant, young lady!' To the baffled looks of the team he held his hands wide apart, then brought them much closer together. 'Hang on, let me -' and he twiddled the computer controls. Abruptly, the Faterpillar shrank lengthwise as the series of disks that made up it's body butted up against each other snugly.

'Oh wah!' said Beatrice. 'That removes at least seventy per cent of their surface area. Rose, you are a genius!'

Feeling entirely unworthy, Rose nodded politely.

'A good beginning. What else can we focus on?' asked Graham. 'What about Sillipedes?'

Beatrice continued to work on the mathematics, physics and physiology of a condensed version of the Faterpillar, mostly because it was the prevalent species across this hemisphere. Given the surface area of a truncated Faterpillar, she was able to work out how much radiation the creature could safely absorb.

The Rutan took careful observation of interaction amongst the human discussion teams, safe behind it's simulacrum, even managing a few quips. The trick was to maintain a convincing façade whilst still maintaining full Dissociation, an aim that got harder the longer immersion in an alien culture lasted.

On the subject of aliens, that alien Smith had seemed to be a potential threat, until making a stern warning about trying to uncover the infiltrating alien. His caution in forcing the humans to work together in multiples was un-necessary – the Rutan didn't intend to cause any more mayhem. Making Cholon speed up research had been merely intended to - speed up research. The ghastly results and ensuing chaos meant disturbance, uncertainty and a greater possibility of being discovered, now that the humans knew a Rutan was amongst them.

Through a combination of luck and selection, the human replaced by the Rutan didn't have any great depth of scientific knowledge, which meant less worry about being revealed in this discussion meeting.

Still, mused the alien, that Rebel Colonist Rose would bear watching. Already she'd come up with an algorithm for the ZLM Prime fauna during the sun's unstable phase. Obviously she ranked alongside Smith in ability.

Most important of all, none of them could contact Earth; the Rutan didn't want any outside influence or information to help the stranded expedition. Assimilate, infiltrate and isolate ran the Rutan Creed. Besides that, those hidden core tubes for the Lowry gave it considerable leverage.

Recognising the trope of a humourous exchange, the Rutan ran through it's reflex library of human responses to same, with a slight randomness thrown in. Dissociation still needed to be adhered to.

Circulating around the Bay, gently encouraging and wheedling, the Doctor acted as a catalyst for the research the teams were doing. Rose found herself caught up in the minutiae of biology, ecology and astronomy after her insight about concertinas.

Arpad, meanwhile, took six hours to manage a barely-effective sequencing with the gimmicked-up electronic assembly presented to him. Having managed that, he ran the specimens for other plants in half an hour each thanks to his experience, and then worked through the fauna specimens. The sequence chains lacked cohesion or completion, the genetic structure predictions were up in the air and his relation of these to protein structures was, frankly, guesswork. For all that, one significant discovery came about.

'Triggered genes,' he pointed out to the Doctor. 'Inactive until a particular environmental stimulus occurs. And they exist in all the specimens I've sampled so far.'

Cocking an eyebrow, the Doctor humphed non-commitally.

'We know what that particular event is. ZLM becoming unstable.'

He cast an eye over the holograms that each team had generated: a condensed form of Faterpillar, a Sillipede that ran on elongated leg-spines, a Weepy Willow whose branches stood erect, and Kink Bushes whose seed pods were veritable forests of writhing tentacles, and other strange variations. Arpad passed on the information about dormant genes, which most people accepted. Typically, Kellerman objected.

'That's ridiculous! Evolution doesn't work that fast!'

Sighing a weary, overly-dramatic sigh, the Doctor shook his head.

'Wrong wrong wrong! Insectile evolution, not mammalian. Far more rapid. Not to mention that the mutation rate will have been over-driven by the regular flare-ups.'

'That's not all. We dissected several Kink Bush specimens and they appear to have a primitive nervous system, if you can believe that!'

Rose felt impressed and creeped-out about that. Weird plants!

'How about the Weepy Willows?' she asked, her curiosity picqued.

That particular arboreal item was in short supply – a few cored samples, bark, leaves and immature seeds were all that were in store for the Willows.

'Let me summarise,' said Christy Taylor, in a tone that brooked no discussion. 'From what we've analysed, and what we already know, the plant and animal life here on ZLM Prime undergoes a metamorphosis when the sun flares up. The sun has flared up. Previously we thought the sun's radiation would cull the wildlife by killing most of it off. Now we know that doesn't happen. So what does?'

'They kill each other off,' finished Arpad. 'Ecological attrition. Then the survivors breed or bud or pollinate up again until the next flare-up.'

Leaning back against a table, the Doctor nodded in quiet satisfaction. The staff had reached the conclusion he'd reached on seeing what had happened to Cholon, by their own efforts and with more details about the mechanics of what happened. Still, the conclusion was pretty stunning: a world-wide state of chaos as the whole flora and fauna strove to survive. No wonder the Trinarians had decided to flee, with a whole planet up in arms around them.

Another thought came to him, one that would confirm their collective hypothesis. He'd need to wait until the radiation died down.

A TEST rat came dancing over to him, tugging at his trouserleg.

'!' it signalled. "Bad plant".

'Oh aye? Trouble at the entrance, eh? Lead on.' He turned to Rose. 'Can you get all the data created here sorted and stored? The rest will need to see it.'

A nervous Montag stood near the baking exterior of the bunker, looking alternately weary and worried. The external temperature had indeed declined, but not as rapidly as Christy's calculations indicated it should: possible evidence that the next flare-up would be more severe and longer-lasting. His eyes felt sore and gritty thanks to the heat, the air outside still rippled and swam, making static objects like the pallets seem to move.

One object that didn't move, however, was the hybrid Cholon-plant creature, which squatted out on the nylon netting like a sinister sentry. It had shambled into view five minutes ago, not getting any closer yet just far away enough to prevent Montag from getting a decent shot at it.

With alarming silence and suddenness, the Doctor appeared at Montag's side.

'Interesting,' commented the lanky stranger, peering hard at the creature outside.

'Interesting?' replied Montag. 'What's it doing?'

'Oh, just the same as any plant or animal species obeying a biological imperative. It wants to replicate.'

'Over my dead body,' muttered Montg.

'Rather – with your dead body,' amended the Doctor. 'Yours and everyone else's.'

TWELVE

The Doctor callled over other staff – Eric and his sister Hypatia - to take Montag's place, with a warning not to move out onto the bunker ramp in order to get a clear shot at the static, forbidding observer outside.

Pulling his trusty, much-travelled and dependable telescope from a pocket, he looked at what Cholon had transformed into: a great, weaving mass of green tentacles sprouting from the neck; from where the shoulders ought to have been the arms had yielded to internal pressure of the plant growth and were now long, rippling strands that the creature leaned forward upon. He shivered, remembering his encounters with Krinoids in the past. This was similar, if on a smaller scale.

Standing at the bunker entrance meant the sentries were beyond effective range of the air-conditioning system. A turbulence created by hot air from outside meeting the cooler air from the bunker caused a modest breeze that served to remind them all how hot it actually was outside.

Eric raised the carbine, at which the shambling green horror outside danced off sideways, awkwardly but rapidly, out of sight.

'Eric!' scolded his sister. 'Now we don't know where it's gone!'

'Quite,' agreed, the Doctor. 'Splendid display of intelligent recognition, though, wouldn't you say?'

Hypatia looked between her brother and the tall stranger. How could a plant be intelligent?

'You're thinking "how can a plant have intelligence",' stated the Doctor, folding up his telescope. 'In this case I think it hijacked some of the cerebral potential of it's victim.'

Both twins wrinkled their faces at this prospect. Neither remarked on how such a process was impossible, not after recent events. The Doctor decided he wanted a more accurate analysis of the Kink Bush and it's rudimentary nervous system.

Rose had gathered together a collection of data-chips with recordings of the discussion team's calculations, together with a set of written notes from Arpad. Everybody dispersed, to get a few hours sleep before the solar activity declined to a safe level. The problem of people sleeping alone or with only one other person present in their cubicle was surmounted by having TEST rats sit en garde, and others chose to pair chairs and sleep in the canteen area.

She felt tired and worried. This whole world was about to come alive and start killing itself, and here she was, stuck there with the Doctor. He'd never consider leaving people in the lurch when he could still help them, and if he was staying here then she certainly wasn't going to bow out.

Not only that, they still had that Rutan spy to ferret out. It had killed one person already, and been responsible for Cholon's death, and Lockwood, indirectly. She and the Doctor would have to track the alien spy down eventually – that was taken as read.

She trudged back to her cubicle, followed by a pair of TESTers. They took up station at the entrance to her cubicle.

'You don't both need to stand guard,' she mumbled. 'One of you should get some kip.' Talking to the giant rodents seemed easier if she pretended they were little people in ragged fur coats. The rats squeaked at each other, one ducking back to curl up under Rose's bed. She accepted this without commenting, not realising until she woke up that, only a few days earlier, the prospect of having a giant rat sleeping under her bed would have given her the billy crins.

When she awoke, the Doctor had joined her in the cubicle. Instead of sleeping he was reviewing the data gathered on the chips, plugging them into a laptop and checking the various redesigns of ZLM's flora and fauna. A TEST rat sat on the bed next to him, exhibiting interest in the holograms.

'Feel better for that?' he asked, looking briefly at her through a translucent hologram.

'I could go a cup of coffe and bacon sarnie,' she replied.

'Only decaf, I'm afraid. Caffeine is illegal. You could have a knitted-soya laminate carefully crafted to look and taste nearly like bacon.'

She pushed back her hair, feeling less hot and sweaty than last night.

'Is it cooler now than it was?' Her companion nodded. 'I'm going for a shower.'

'Don't take too long,' warned the Doctor. 'I want to go out and do a little geophysical analysis. It should be okay to move around outside in a few hours.'

In fact it took six more hours for the radiation to decline to a safe level. Christy wasn't happy at being so wrong with her analysis. Her husband brought her to the Doctor, who had set up shop in the canteen area.

'I can tell what you're going to say,' he warned her whilst examining a sketch of a Razor Tree. ' "I'm not usually so wrong".'

Christy bristled with righteous indignation and plunged right in.

'If you were familiar with solar spectral emissions and cumulative frequency calculi, you'd know that my analysis was correct for the star's initial flare output, Doctor.'

Pausing, the Time Lord looked up at the aggrieved woman.

'Christy, I'm so sorry! I didn't mean to question your ability. What did you want to tell me?'

Utterly undercut by the effusive apology, Christy gaped for a second before recovering herself.

'Ah – I – well, I meant to say that ZLM's output didn't decay the way it has done before. The distribution was skewed towards the last percentile, far too much energy being released by any standard model.'

'Meaning?' asked the Doctor, quite aware of what this meant.

'ZLM may be entering a chaotic state, where it's activity is neither predictable nor regular. A supernova in the offing, with no guarantee it won't happen tomorrow!'

The Doctor tapped his teeth with his sonic screwdriver.

'So. The Trinarians get their supernova alright, just a few hundred years later than they anticipated.'

'Don't argue mathematics with him,' observed a passing Amir. 'I tried.'

'Let's look outside,' the Doctor decided. Rose, underemployed and bored, jumped to her feet and followed as he led a small procession to the bunker entrance. Hypatia had taken over the carbine from her brother, who was dutifully checking the wall-mounted thermometer.

'Safe to exit,' he called to the small group.

'Excellent!' beamed the Doctor. 'First we need digging equipment.'

Rose ventured into the Stores bay, returning with an armful of spades, a pick and several trowels.

'Top stuff,' declared the Doctor, stepping gingerly onto the exit ramp. It remained hot underfoot, and a stink of over-cooked plastic came from the nylon anti-erosion webbing.

Rose sniffed daintily, then made a face at the acrid fumes from the netting. She looked up at a sky still stained an angry scarlet, with thin high clouds scudding along. A faint breeze wafted sand and scents over the Defensive Dyke, which seemed to be their destination.

Taking a trowel, the Doctor incised two parallel lines about a yard apart, running from the inner base of the wall to the top.

'I need to have a vertical slice through this structure. Gworn at it!' he declared, attacking the wall with a spade. Casting curious glances at each other, the small group of hangers-on now began to dig away. Rose wielded the pick for a few minutes until her arms got tired, then dug with a spade until her legs got tired, then trowelled until her hands got tired, at which point she sat on the narrow edge of the Dyke's rampart.

Looking out over the landscape, glad of a vista other than the grey bunker walls, she noticed that the distant air still rippled and danced with heat, creating optical illusions. If it was still hot out here, at least it lacked the humidity of Serendipity's bunker, with all those people stuck together.

'Hey!' came a shout. 'I found bones!'

The finder was Dan Barthelmy, who carefully balanced a long, greenish object on his spade.

'Look at this. One of your reptilianoids!' he joked to Rose, before turning to the Doctor, whose long, lugubrious expression killed the humour straight away.

'Let me see,' asked the Time Lord, delicately picking the bone up and examining it. Friable thanks to time and decay, he took careful note of the multiple holes bored into it. Anchor points for invasive plant tendrils, he guessed. The green coloration was not only due to bacterial action, either, because when he snapped it open, a chlorophyll green persisted across the entire depth of the bone.

'There's more,' added Dan. In the whole afternoon of digging and excavating, they uncovered a Trinarian skeleton (complete, if scattered) and the partially-preserved remains of a Big Bug, it's chitin brittle as eggshell. Various scales and tines might have been the eroded remnants of a Sillipede or two; it was hard to tell given the degree of disintegration. At the Doctor's insistence, they took a cored sample from the top of the Dyke, screwing the bit a good two yards down before retreiving the column of earth.

'Any rats about?' asked the Doctor, as one skipped into view from the other side of the Dyke. 'Go and ask Graham Chadwick to prepare to analyse a core sample.' He stood and straightened his back, stretching out the kinks. Unlike everyone else, he hadn't even broken a sweat. 'We've done enough. Time to get back inside.'

Rose took another shower to get the sweat, dust and grime out of her hair, before returning to see what the core analysis showed. To her it was just a long plug of earth, laid out on a translucent tabletop, over which Graham and Barry were fussing with electronic probes and an X-ray wand.

'Unusually high organic content,' murmured Graham. 'Plus a talon from one of our alien giants.'

'Looks like earth to me,' commented Rose, sticking her hands in the boilersuit pockets and swinging her hips.

Graham made a face. He continued to poke away with electronic probes for long minutes before stopping and facing the Doctor.

'This is intriguing, Doctor Smith. Together with the usual silica, wind deposited material and so on, there's a great deal of humus here. Derived from organic sources, including the giant insects we see regularly. However, it's all been sterilised.'

'Oh, now that is interesting1' remarked the Doctor. 'And worrying,' he added, after a second.

Rose looked at him in the way that implied a question without having to say anything.

'I think we need to get everyone informed about this. This – this is serious,' said the Doctor, pointing at the core sample.

It still looks like earth to me, mused Rose.

It took some doing to get everyone assembled in the canteen area, including a bevy of the TEST rats, who sat discreetly under tables, bobbing characteristically up and down with muted excitement. The Serendipity mission staff bunched in cliques, casting glances at those they disliked or disdained, until the Doctor wheeled an adapted monitor over to the far wall.

When he pressed the power button, an immense square of bright white light sprang into existence on the bare bunker wall, as if a film projector were at work. Using a marker pen, the Doctor sketched in a large circle on the monitor screen, projected onto the wall. At the centre of this circle he added a rectangle, and off to one side drew another smaller circle.

'This rectangle is the Serendipity bunker,' he explained. 'The large circle is the outer formation you called the Dyke, and this smaller circle is the take-off point for the Trinarian shuttle.'

'Thanks for the lecture,' said a bored voice. Rose, stood at the back, glared in the general direction of the speaker – probably Kellerman, she thought.

'Thanks for the unhelpful sarcasm,' the Doctor dashed back. 'Pay attention if you want to live!'

He drew a small red sun up in one corner of the display.

'Fact one. ZLM becomes unstable.' Radiant waves were drawn around the sun.

'Fact two; all life on ZLM Prime goes beserk under the influence of the star's increased output.'

Next a scraggly-looking Kink Bush was added, outside the Defensive Dyke.

'Fact three: that wildlife attacks the Trinarians in their bunker and outside.'

'How do you know that?' asked one of the staff.

'Because we sampled the Dyke in cross-section. Your description of it was utterly wrong, assuming it was built by the aliens to keep hostiles away. In fact the Dyke is composed of that very same hostile life.'

A series of rays were now drawn on the picture, shooting out from the bunker.

'Fact four: the Trinarians use their stored energy weapons – presumably based on the bunker roof - to utterly devastate the initial attacks by hostile ZLM lifeforms. That explains the steep outer wall of the Dyke, when masses of attackers were blasted into ash and splinters. A great wall formed.'

Stopping to look at the audience, the Doctor saw he had them hooked. Even the dismissive Kellerman looked anxious.

'However. The attacks did not stop, and the Trinarians only had a limited energy budget. Those hostile lifeforms kept on coming, being destroyed again, but less effectively. They got progressively closer to the bunker before being destroyed.'

A new dotted line was added to the picture, between Serendipity bunker and the smaller circle.

'Fact five: the Trinarians abandon their bunker after sealing-up three volunteers to keep manning the weapons whilst they make an escape.'

Next, he added an arrow to the small circle, scrawling off-screen.

'Fact six: the three trapped volunteers keep most of the attackers away from the shuttle. Those few organsims that do reach it are blasted apart by the fusion boosted takeoff.'

Finally, he drew a basic skull-and-crossbones over the bunker.

'Fact seven: trapped inside their bunker, with no way to get off-world even if they managed to get out, the three volunteers all commit suicide.'

This simple, step-by-step progress over the alien's demise created a few seconds of silence, before conversations broke out amongst the dozens present.

Eric French stood and made his way over to Rose.

'We've had it!' he hissed. 'Those plabby aliens were armed to the teeth. There's only forty of us and what have we got? A carbine and two pistols.'

Rose stared back at him.

'I don't think the Doctor's finished.'

Indeed he had not. Instead he stood in a confident pose, hands clasped together behind his back.

'I apologise for alarming you all. Before anyone panics, please realise that you have a great big advantage that the Trinarians didn't – you have the Dyke.'

Various scoffing comments began.

'Because,' added the Doctor, raising his voice. 'Because it blocks off the site from any external observers out in the distance. There's no reason to expect an attack here for the simple reason that you're out of sight.'

A small group of the staff met in Roj's cramped cubicle afterwards, including Graham and Kendall.

'You missed out the roving monster that Mike's become,' said Kendall.

'A single creature we can kill with a spray from a fire extinguisher,' replied Arpad, standing shoulder-to-shoulder with the Doctor.

'Or a spray of paraquat,' muttered Rose, standing forgotten in a corner whilst all the busy, bright scientists chatted together.

'What I still don't know is why the massed ranks of hostile lifeforms attacked the Trinarians, kept on attacking and didn't stop until there were no more Trinarians to attack,' finished the Doctor.

Amir had been sitting cramped into a corner, reading a hastily-assembled set of notes transcribed by one of the other staff, flicking back and forth between the pages of the spiral-bound plastic book, cocking his head in a thoughtful manner and slowly scratching his thinning hair.

'I think I know,' he said quietly, his words lost in the busy hubbub of other people's arguing and discussing in the confined space. 'I said - ' he began, before Rose insistently ssshhhd! those present.

'I think I know why the plants and animals – insects, really – why they all attacked the Trinarians. Radiant energy.'

Alone, the Doctor snapped his fingers and looked impressed. Amir glanced at him before continuing.

'These life-forms are adapted to utilise a gigantic input of radiation into their ecosystems. Once the sun died back down again, the Trinarian's ray-weapons were a close parallel. If they fired at even a single attacking plant, every other life-form within range would detect that energy source and come to try and tap into it.'

'Their ray-guns disintegrated anything they hit,' objected Kendall. 'That doesn't make sense.'

'Oh but it does!' interrupted Roj, before the Doctor could get a word in. 'The area-square rule means that any energy emitted concentrically from the main weapon discharge would decrease proportionately over distance and any organism perpendicular to the axis of the beam - '

He stopped when Rose waved at him.

'In plain English, please,' she asked, a touch grumpy at having to ask.

'Translated,' said the Doctor, stepping into the conversation. 'If the Trinarians fired a weapon, the newly-changed ZLM Prime wildlife sees it as a free energy-buffet. They come running.'

'Ooh!' exclaimed Arpad. 'A positive-feedback cycle. How dangerous!' He caught Rose's eye on him. 'That is, the more these aliens fired their deadly energy weapons, the more they attracted hostile wildlife.

'

'That's good news!' beamed Roj, almost sounding like a mission leader again. 'We've only got that single police carbine to worry about. Where is it?'

'I put a sentry on the bunker entrance with it. Just in case that mobile bush turns up,' said Graham Chadwick. 'Plus, Barry is drawing up a rota to ensure it can't sneak back in.'

'I think the emergency is nearly over, then,' said a happy Roj. 'We only have to stay in the bunker until things die down, literally.'

With a scraping of feet and chairs, the meeting broke up, until only Roj, the Doctor, Rose and Arpad were left in the cubicle.

'It's not quite that simple, is it?' asked Rose of her mentor, recognising his anxious stance.

'No,' he agreed. 'Roj – nobody's yet accounted for those missing hundred and seventy five Trinarians.'

'It's a big planet,' said Roj, paying more attention to the data backlog percentages on his monitor than the Doctor. 'They ran off and died.'

Rose found that instantly preposterous.

'Ran off into a planet full of raving monsters! Try again!'

'I rather suspect that they became those very same raving monsters,' added the Doctor.

Arpad and Roj looked at him, both startled.

'I selected a part of the Dyke to cross-section at random and we still came across a Trinarian skeleton, from an alien thoroughly infested with mutated Kink Bush. I bet if you chose any section at random and dug, you'd find similar remains.'

Arpad felt a horrid rippling sensation on his forearms.

'Doctor Smith – Cholon was attacked and transformed by accident. You surely aren't suggesting that one hundred and seventy five accidents transformed the Trinarians, are you?'

The flat, emotionless look he got in reply made the hair on the back of his neck resemble his arms.

'By intent? They – they infected themselves deliberately!'

The Doctor shrugged.

'Until Nils and Kirsten can translate enough language to find out why, I can only guess why they chose to become infected. At a guess, their homeworld had been over-run or destroyed by the Rutans or Sontarans. Some of them didn't want to go back to a radioactive cinder in space as a home, so they intended to stay here.'

Arpad shivered in distaste, a reaction that Roj mirrored, and the mission leader found his recently recovered aplomb vanishing again.

The Doctor refrained from commenting on yet another potential peril, that of the Lowry hyperspace coil. He understood that their Rutan infiltrator had hidden the core tubes to isolate the mission. However, even if they were returned, using the giant transmitter would send out infrasonic emissions guaranteed to bring every local plant or animal hotfoot; hotfoot and hostile and hungry.

Therefore, no emergency transmissions pleading for the mission to be recalled. Even if they got the core tubes back. Even if – well, no use pondering on possible negative outcomes before they happened when nothing could be done to prevent or diminish them.

'I think it's time I took a well-earned nap,' he informed the bunker at large. 'Recharge the batteries. Call me in eight hours.'

Rose scurried behind the lanky-legged traveller as he sped back to their cubicle.

'D'you want me to do anything?' she asked, fearful of sitting bored for eight hours in the progressively-less stifling bunker. 'If you don't I might go out for fresh air.'

'You can get together any information about the Kink Bush's nervous system, if you like. Or - ' he added, seeing Rose's face fall. 'You can go out and get a bit of sunlight. But be careful!'

'I'll take a fire-extinguisher!' chirped Rose.

Leaving the grey-walled Serendipity bunker again, Rose felt as if she'd cast off an outer casing of dull gloom. True, outside was dangerous with that roving plant-monster, and still baking hot – far hotter than Torremelinos – but you could look to the horizon and the sky wasn't a roof ten metres overhead.

Looking up, the sky still had a pink cast to it, with rapidly-flowing thin streamers racing and threading between themselves. ZLM itself presided over all with the weary air of a sun that had seen it all, wasn't impressed and wasn't going to last much longer.

Rogan and the Frenchman – Dan, that was his name – sat at the entrance to the bunker, Rogan wearing a wet towel wrapped around his head, turban-fashion, holding the carbine in a casual manner. Dan appeared to have his eyes closed, yet still managed a "hello Rose" when she walked past. A torpid TEST rat lay at their feet, acknowledging her with a wave of its paw. A wary woman – Beatrice – sat opposite the two men, sighing in the heat, fanning her face with a hand and sucking an ice-cube pilfered from a canteen freezer.

'Stay in sight of us,' warned Rogan. 'We've not seen that fnorping vegetable monster, but I don't want you taking chances.'

'Just going onto the roof,' she replied, swinging the aerosol fire-extinguisher. Walking round to the soil-covered bulk of Serendipity's side, she hoisted herself up a narrow track, keeping upright by pulling on plants and roots, ones safely inert.

Must be too small to go weird, she mused, finally standing in the large, basin- shaped depression on the very summit of the bunker. The recent ferocious heat had dried it out completely, leaving a crazed pattern of big mud flakes. Not very comfortable to sit on.

Mind you, the view from here, the highest ground for kilometres in all directions, was still splendid. Rippling grasses, waving trees, and a hazy horizon where the fogged-over landscape edged indefinably into the sea. If an observer didn't know the mayhem and horror that lay out there – and which still seemed a vague impossibility – then it looked as serense as Paradise.

'Be careful, Doctor,' called Dan from below, catching Rose's attention. A mumbled response she couldn't make out followed.

Has he changed his mind and come out? She wondered if he'd come out after her and of course he wouldn't know where she was. Dan and Rogan clearly hadn't directed him to find her.

Down the dry, friable soil-covered bunker side she skidded, racing across the nylon netting thanks to gravity, and catching sight of a long coat vanishing around a giant, dusty pallet.

By the time she sprinted over the Doctor had moved on again, and she had acquired a stitch and couldn't call out, let alone move quickly. Leaning against the pallet, she heard a bizarre and unpleasant sound, as if a cabbage was being shredded by a vacuum cleaner, in a vat of soup.

Rose opened her mouth to call out, before deciding caution triumphed over volume, and sneaked around the pallet.

What she saw made her open her mouth again, but this time in shock and horror.

THIRTEEN

Rogan sat and wondered about how he could save everybody from a dreadful fate and return to Earth feted, rich and famous. Considering their position here on ZLM Prime was so dodgy, he'd settle for simply returning to Earth.

Not by using the police carbine, that much was certain. It had enough charge left for about twenty shots, and a spare power-pack good for another thirty shots, and then it would be a large, expensive club. You couldn't beat off a whole planetful of plants with that.

What could he use from Stores? What did they have that was incendiary or fatal to plants? They had fuel capsules for the motor vehicles, which had potential as containers of volatile fluids.

'Did you hear that?' asked Dan, opening his eyes and frowning in concentration.

'Eh? What?' asked Rogan, jerked from his semi-serious reverie.

'A commotion out there,' replied the other, nodding towards the checkerboard of giant pallets.

'Isn't Rose still up on the top?' asked Beatrice. 'Rose!' she called, suddenly and loudly.

No reply.

Feeling uneasy, in a way he couldn't rationalise, Rogan stood and called out the young woman's name again.

Still no reply.

'Come on,' he said. 'Dan – you heard it, you lead the way.'

The Doctor looked at the garden gate in front of him. Made of white latticed wood, it swung open without a sound when he pushed it. The arbor led into a mossy, greened-over graveyard, full of heart's ease and flox, Red Admirals and high-pitched birdsong. A benificent sun shone down over all, lending a drowsy ambience to the scene.

'Nice,' he observed, strolling along the flagstones. 'Very twee.' Out of a certain morbid curiosity he stopped to peer at a headstone.

"Katerina" he read, and moved swiftly to the next one.

"Adric", he read aloud, and decided not to read any further.

'Chicken,' said a muffled voice from the other side of the graveyard. The Doctor looked up, to see a six-foot tall rabbit wearing a waistcoat, nonchalantly leaning against a wall, looking back at him.

'Harvey, I presume?' he replied, with a touch of acidity.

Immediately the rabbit looked annoyed.

'Excuse ME!' it snapped. 'If you will observe my apparel, it is obviously nineteenth century English plaid weave, predating the Broadway play and Hollywood film by a century at least.'

'Oh,' replied the Doctor, temporarily nonplussed. 'Sorry. Are you a figment of my imagination?'

Once again the rabbit looked annoyed.

'Really! No, I am nothing of the sort. I am your subconscious.'

The Doctor stuck his thumbs into his belt buckle and rocked back on his heels.

'I see. You know, in times past my subconscious had more dignity. This is rather a caricature of a parody. An English Country Garden indeed!'

The giant rabbit rolled it's eyes in a very human way.

'Oh tempora, oh mores. Look, Doctor, this is a representation of what you're worrying about. The living world, growing things, plants, biology, horticulture.'

The Doctor stopped rocking on his heels.

'Why a giant rabbit?'

Another shrug from the creature.

'Fecundity? Proliferation? Honestly, I'm just your subconscious at work.. Don't expect me to know what I mean.'

This is all very confusing, said the Doctor to himself. If I was awake then this ought to make more sense.

'You want more sense?' asked the rabbit. 'Okay.'

In so short a time that it barely registered, the idyllic churchyard vanished, being replaced by a small room occupied with a major computer installation and dozens of chrome-and-leather chairs. The rabbit had gone, replaced this time by a tall, white-haired man with a prominent nose, whose eyes glinted with both intelligence and mischief. He wore a smoking jacket and a ruffled silk tuxedo, and managed to look completely out of place and quite at home simultaneously.

'You!' exclaimed the Doctor.

'Quite,' replied the other man, rubbing his nose absently with a forefinger. 'Or, maybe, "Me!".'

'Why have you appeared?' asked the Doctor, warily. This wasn't so much a blast from the past as an –

'Oh,' he said.

'Ah,' replied the other. 'You see the link I've made, being your subconscious. Fire. Inferno. Fire.' He looked at the Time Lord with gimlet eyes. 'Nor will you forget this dialogue between different parts of your mind.'

A little chastened, the Doctor decided his subconscious needed a bit of praise.

'Thank you.'

'Not at all,' replied the other, with the patrician air of a man long used to getting praise. 'Oh - and don't forget about reversing the polarity of the neutron flow.'

That caused a mental twitch in the Doctor's thoughts.

'But a neutron doesn't have a charge - '

'Hush!' cautioned the other man. 'Time to depart.'

Abruptly, as if emerging from a cave, the Doctor found himself back in complete wakefulness.

His hyperthalamus still registered the disconcerting effects of ZLM on local space-time, making any transit in the TARDIS a bad idea at best.

More to the fore, however, were the calls and sounds of alarm in the middle distance. Checking his watch, it became obvious that he'd only been asleep for half an hour. Sighing and brushing his hair back into place, he darted out of the cubicle and ran towards the commotion, trailed by a pair of TEST rats.

Kaatje Pierson, wailing and inconsolate, stood outside Biology Bay and waved a large scrap of plastic paper. A small group of the concerned had gathered to see what the bemoaning concerned.

'The doctor! The doctor!' she blubbered. Eyes flickered backwards and forwards between her and the Doctor, who read their intent with the ease of long practice and experience; after all, he was an alien here on sufferance.

'Get a grip,' he growled unsympathetically, causing the snivelling woman to stop snivelling in sudden surprise. 'What is the matter?' he continued, a little more pleasantly.

'She left a note. The doctor left a note. She couldn't go on without her husband so she's gone out to join him.'

'And you let her!' accused the Doctor, ferociously. 'That – that's a suicide note!'

'I only just found it,' sniffled Kaatje. 'It's not my fault.'

'She should – oh never mind,' replied the Doctor, biting off his observation that a little more care and concern about the grieving widow would have helped more than all this breast-beating now. He hadn't taken time to consider her, had he?

'When did she leave?' asked Arpad, appearing behind the Doctor.

Kaatje shrugged miserably.

'Er – I don't quite know. Ah – Thijs and I – uh – well, we went for a cup of coffee and when we came back - '

'You left her alone?' said an aggrieved Arpad. 'What were you thinking!'

'I got your coffee and a toasted slice of soy-bread!' announced Thijs Pierson blithely, elbowing past the small group. 'What? What did I do?' he asked, seeing hostile glances directed at him.

The Doctor, however, was no longer around to listen. He was heading at speed for the bunker entrance ramp. Rose was out there, and he had a nasty feeling that she might very well try to talk Delgerdzaya out of self-destructive behaviour, which would put her in harm's way.

What she saw in those few minutes upon the bleak earth of ZLM Prime would stay with Rose for a long time.

The person she had trailed was not her Doctor. Rather, it was a doctor. Doctor Choldongorzy, whatever her surname was, wearing a long lab coat over her issue boilersuit. She had heard Rose come panting around the corner of the pallet and turned to cast a last, careless look over her shoulder, her face a mask of pain and emptiness. Then she looked ahead and walked on.

Into the embrace of the monster that her husband had become, a mass of enslimed green tentacles writhing up from a pit it had dug into the ground, burrowed into the loam like a mole, or a trapdoor spider. No wonder nobody had seen it, hiding below ground and out of sight.

Bizarrely, and hideously, the mass wasn't simply an undifferentiated clump of tentacles. There seemed to be a central mass, where a human torso would have been, and a smaller one atop that – like a head. And two long clutching arrays similar to arms, that reached out and enfolded Doctor Khongordzolny, dragging her into the central mass without a sound.

Jaw sagging in disbelief, Rose gasped in shock and backed away. This made it twice that she'd been closer to this thing than she ever wanted to be. And the doctor! She'd just walked right into the ghastly thing's waiting grasp – as if she wanted to die.

The creature bulged and pulsed, it's victim now hidden completely from view within the striated tentacles. Long seconds ticked by.

'Help!' Rose squeaked. 'Help!' she tried again, far louder. 'HELP!' she finally yelled.

Hunched over itself, the plant-creature stopped it's writhing immediately, the small grouping of tentacles where a "head" would be turning to sense where the sound had come from, waving back and forth until they stopped, pointing directly at Rose.

Who ran. Back around the pallet, back towards the Serendipity bunker, and straight into the arms of Dan and Rogan.

'Whoa there!' said Rogan, almost bowled over and nearly dropping the carbine.

'Careful with that!' snapped Dan, well aware that the lethal weapon would make a very big hole in whatever it hit, regardless of whether that was hostile plants, the ground or a person.

Beatrice, following a little more leisurely, recognised the wide-eyed terror in Rose's eyes, and immediately sought to console her with a generous hug.

'What is it?'

'That plant thing! It's right there! And the doctor – Mike's wife – she – she - ' stammered Rose.

Rogan took a deep breath and dodged around the corner of the pallet. All he saw was a yawning pit, a good six feet deep, and disturbed earth around it.

'Not here now,' he called back over his shoulder, scanning in all directions.

'It was!' asserted a tearful Rose. 'And it got the doctor. She just walked into it.'

'Shhh,' comforted Beatrice, stroking Rose's hair. 'You need a sedative.'

'Oh, I don't know,' said a familiar voice. 'I never was one for better living through pharmaceuticals.'

'Doctor!' choked Rose. 'I followed the doctor – the widow – thinking it was you. And that monster got her!'

Rogan returned, walking backwards in order to keep the carbine pointing at the pallet-field.

'Listen, there's fifty of these pallets arranged over half a square mile. I don't fancy trying to track that thing down in a maze like that.'

'How are you?' asked the Time Lord, in a concerned tone.

'Wellll - ' began Rogan, pretending to misunderstand, and making Rose laugh a little.

'I'll live,' she said, through a noseful of mucus. She proved this by turning to the Irishman. 'You could use the TEST rats to be your scouts if you're looking.'

Rogan snorted.

'As if! What do you – Ah,' he corrected himself. 'Now, you know, you may have something there, lass. Sorry, fem.'

Two hours later Rogan reported back to Roj and the Doctor. He had taken Rose's suggestion to heart, and organised a hunting party of a dozen rats, who swept across the whole compound twice, not finding any trace of alien plants or their victims. He had followed them warily at first, then resignedly, then with boredom. Dan and Beatrice came after him with an induction pistol between them, ready for any minor unpleasantnesses ZLM Prime might bestow.

'Nothing,' he reported, slumping into a chair, taking a big bite out of a slice of toast. 'We quartered the whole area, twice, didn't find a trace of the fnorping green tentacle monster.'

'No more hidden hidey-holes?' asked Roj, nervously. His attitude had not regained the heights of self-assurance of yesterday.

'Nope. None. We did find a trail leading over the Dyke that might have been this thing escaping, but nothing conclusive. The ground's baked too hard for any clear tracks to be left.'

Roj breathed a conspicuous sigh of relief, then tensed again, realising that the Doctor didn't seem equally satisfied. Surely getting rid of the killer plant was a good thing? If it left them alone for the forthcoming hiatus while they couldn't send out an SOS, then they were doing fine, surely?

'I'm not happy,' declared the Doctor.

He wasn't. Getting it completely wrong about the ecology of ZLM Prime rankled with him, whatever excuses he might make about only just arriving or unfamiliarity with the ecosystems. On top of that, he now had a parasitical monster that had killed two people – three if you counted Mike, the original victim.

'When Eric tried to use the sights on the carbine to look at it, the hybrid took off at high speed. Now we see it engaging in ambush behaviour. Ambush behaviour!'

Roj looked at the Time Lord blankly.

'Is that important?'

Trying to remind himself that the mission's leader was more familiar with solar maxima and nuclear fusion than with predatory behaviour or photosynthesis, the Doctor paused to remain calm.

'Roj, it's no longer a plant! What we're seeing is – oh, I dunno, a new classification in the phyla. Not a metamorphon or symbiont, nor a parasite, nor a hybrid, but a combination of all three. That plant has accessed part of Cholon Khongordzolny's brain.'

Probably via micro-tubule invasive penetration of the cerebellum's structure, down to the cellular level, he continued to himself. The altered Kink Bush literally ate it's victim's brain from the inside. Some aspects of the parasitization process were similar to those of the Krinoid, except that these hybrid creatures were merely using a fraction of a fraction of the original owner's brain.

Rogan made a face. Dan didn't, simply because he didn't want to acknowledge that someone he'd liked and respected had been transformed into a killing vegetable.

'It's got Cholon's knowledge?' asked Beatrice, horror-struck.

'No!' snapped the Doctor. 'Or rather, yes – but a very qualified yes. It accessed a fraction of his brain before his death. It can thus think, in a very crude fashion.'

In the country of the blind, mused Rogan. His specialism was geology, so he chose his words carefully.

'A plant that can think. Even if it be ever so crude, Doctor Smith, that makes it king of the plant kingdom instantly. Eh?'

The Doctor nodded.

'It's very dangerous. Very dangerous!'

Out on the grassy plain, what had once been a human being stopped and cast around, using the sensitive hairs on it's tendrils to sample the wind and what it carried.

Seeds, moisture, a scent of sap.

The creature didn't think of itself as "It", any more than it considered the newly-created writhing mass of tendrils nearby as another, fellow creature. What it knew was that those fragile beings left behind made good hosts, mobile and adaptable.

There had been a difference, too. Muddy thoughts slowly moved inside the hybrid, the residue of an intelligence that had been partially-usurped. Not a novel circumstance, but the last time it happened had been over eight centuries before.

With a loud rip, the boilersuit and lab coat covering the other transforming creature split, allowing the mass of tendrils to escape and quiver in the dusky light.

Quick, realised the Cholon-thing. A concept new to it. Quick change. Then, it associated the rapid alteration of that victim with the long, slow and incomplete change of the other victim in the confined space. Slowly, the organism brought together the massive invasive attack it had made on this creature and the speed of transformation.

Suddenly, it detected movement nearby and swung to face the object. It picked up the release of a suppressive scent, exactly the same as the scent it could release itself.

This object was small. If the transformed creature had possessed eyes, it would have seen a Big Bug, riddled through and through by Kink Bush tendrils that gave the macarbre illusion of being pantomime hair.

Neither of the infested creatures moved, at least not until a Sillipede ran between them on it's elongated spines. Fast as it was, both it's attackers were faster, and neither were remotely deterred by the slashing defensive spines. They tore it apart and absorbed the fluids that came spurting out, for additional sustenance. Both could feel the sun's rays fading as the long day of ZLM came to an end.

Silently, the second transformed ex-human stood up, using bones beneath a living shroud to articulate and move, and the hijacked human brain, overgrown with roots, to form vague thoughts.

Imperiously, the original creature extended a long tendril, catching the newer one and pulling it closer. When the new arrival turned to the Big Bug with aggressive interest, it's creator slapped down the tendrils.

That creator was forming more novel concepts.

Leader.

Yes, Leader. And –

Attack.

Roj and Graham were trying to make sense of what the Doctor's experience of similar situations told him were appropriate tactics.

To him, it was obvious. Having many encounters with besieged human missions on Earth or elsewhere to his credit, he knew the first essential was to get everyone on the same side. You simply could not begin to resist or fight back unless you were unified. Secondly, you used the resources you had, instead of trying to create new ones. Thirdly, you played to your strengths – if any – and the enemies weaknesses.

Knowing this and trying to convince the mission was difficult, of course, especially since there were so many divisions and dislikes between members. The presence of a Rutan infiltrator didn't help, either. Nor did Kellerman, the spy. Nor did Roj, really, since he was not dealing with the truths that faced him. Not that people were inclined to take the Doctor's word on trust, not with his alien background. The only person's loyalty he could take for granted was Rose's.

What he also needed was an inventory of useful materials, as an idea took root – the irony of which, once again, did not escape him.

'I take it that you have lots of construction materials to spare, that you didn't use because you found the bunker instead?'

Roj called Rogan up and asked, via wrist-phone, what the situation was with regard to spare construction materials.

'Literally tons,' replied the storesman. 'Everything from trowels to pre-cast concrete blocks.'

'Scaffolding? Reinforcement rodding?' asked the Doctor. 'Nylon netting?'

'Miles of the first two and acres of the last. Can - '

'Splendid!' grinned the Time Lord. 'Let's get to work, shall we?'

A small group of expedition members trotted out from Serendipity and into darkness, carrying hammers and shovels and cabling and banks of portable lighting. They split into two, half a dozen heading for the Defensive Dyke, another six making for the pallet field.

This second group returned to the perimeter carrying rolls of heavy-duty nylon netting, scaffolding poles and dozens of three-foot reinforcement rods. Under the Doctor's initial guidance, they hammered the smaller rods directly into the top of the dyke, spacing them well apart in order to completely traverse the structure. The longer, heavier and far more awkward scaffolding poles took a lot more work, requiring holes to be dug and cement be mixed to give them a solid foundation. Before the cement had even set, the Doctor was unrolling nylon net and weaving it between the poles and rods.

Given the length of a ZLM Prime night, it was still dark when they finished, dirty, sweaty and close to exhaustion.

The Doctor stood back and admired the team effort. Yes – this was one of the reasons he liked human beings: they were clever and they worked hard. A giant black ribbon of matte black nylon six feet high stood out against the night sky.

'It's not going to keep much out, you know,' muttered Nils Gundarsson. 'Anything that can climb will get over that netting.'

'We've only haf-finished,' remarked the Time Lord, off-handedly. Despite working just as hard as anyone else, he remained remarkably sweat-free and tidy. 'That was the long, hard safe bit. The short, dangerous bit comes later.'

People exchanged looks at that.

'Not much later,' continued the Doctor. 'Darkness is our friend.'

The dirty work party took turns in getting showered and creating arrays of cocoa or mock-tea or psuedo-coffee, gradually ending up clustered in a corner of the canteen. Since human circadian rhythms insisted that it was in fact six o'clock in the morning, a few early risers came to join the recuperating workers.

'Fight fire with fire,' announced the Doctor, to puzzled looks. 'Metaphorically, on one level. I meant, we combat the hostile alien plant life with other hostile alien plant life. Literally, by using torches with a little red plastic applied.'

Rose, having slept fitfully and with snatches of monster-ridden nightmare, came early to the canteen and found a cluster of people listening to the Doctor. After a few seconds earwigging she realised he was describing a method of keeping the hostile plant and hybrid organisms from the site, by using local resources. When he asked for volunteers there were few takers.

'I'll come,' she said, between huge yawns.

'I'm not sure about that,' drawled the Doctor, casting a chilly look around his audience. 'Unless there are more volunteers?'

Eric French stuck his hand up, the attraction of Rose defeating the repulsion of dangerous ZLM Prime plants.

Ten minutes later Eric felt less brave as the Doctor sat behind the wheel of a Rapid Rider, driving more by sense than sight. He would turn the headlights on for a second and then navigate in the near-darkness for up to half a minute. At first their departure from Serendipity was quiet, with the caterpillar tracks of the vehicle soughing gently over soil and grass. Then the sounds were interspersed with brittle crunches which became part of the background before dying away again, and at one point what sounded like a miniature hailstorm broke on the cab sides. To Eric, it sounded like driving over acres of overdone toast.

'I hope we're in time,' worried the Doctor aloud.

'In time for what?' asked Eric. Rose might have asked the same question if she weren't feeding crusts to TEST rat 3.

'To do our pruning and get back before daylight. You noticed all that hybridised wildlife we drove over?'

The crunching? That was what it had been?

'I think the locals are creating a perimeter. We have a day, perhaps two, before the bunker is surrounded.'

Eric sat upright at this news. Unwelcome news.

'You said they wouldn't attack us!'

Flicking the headlights on, the Doctor narrowly avoided hitting a tree. Prior to ZLM's flare-up it had been an etiolated Weepy Willow. Now, it threshed in warning. He didn't want to bestir the quiescent plants by using the full-beam for any length of time, hence the sparing use of the headlights.

'Ah, yes, might have been a bit out on that hypothesis. Didn't take into account our friend the Cholon-hybrid. It may be organising the locals.'

Frankly, this seemed a bit much for Eric. Intelligent plants?

Abruptly, the Doctor's night-driving skills and luck ran out, just as he flicked the headlights on again. Eric glimpsed the tall, stately shape of a Weepy Willow as the Rapid Rider slammed into it and the vehicle cargo came crashing down on him.

FOURTEEN

Kendall Kellerman nodded to himself, looking around at the others who'd slowly gravitated to a corner of the canteen.

'Don't whisper,' he warned them. 'That's a giveaway. Normal tones. If anyone else comes nearby, switch to discussing why you got sent out here.'

He looked them over again. Not impressive, but then they'd do as stalking horses. The Schoonmaker sisters, Monday Lockwood (Harry Lockwood's less-than-grieving widow), Arthur and Vicki Dawson and Swoozie, his work partner as a Humper and Dumper up until his true nature was revealed.

'You're here because you think like me: Doctor Smith is an alien and can't be trusted. What's he got to gain by helping us? Why can't we make a run for it?'

Nobody agreed with him out loud, but at least they didn't disagree with him.

'Why should we make a run for it?' asked Beatrice Schoonmaker. 'We're safe in Serendipity. Food, water, shelter, heat, light – we've got it all.'

Kendal sighed, insincerely.

'There's only forty of us left. We've got three guns and that's it. There were over two hundred aliens here, armed to the teeth, and they got over-run. I don't intend to stick around and repeat their mistake.'

Especially not when I can have you lot as my personal human shield, he added mentally. He was quite willing to sacrifice a couple of them to get his hands on the plasma carbine that whoever stood sentry at the bunker entrance would be cradling.

'So what's your plan?' asked Beatrice. Her sister nodded coolly, making Kendall realise he needed to sell this plan persuasively.

'Not complicated. We take the second Rapid Rider, after we sneak out supplies to it. Like you said, food, water, stuff like that. Load it up in secret for a couple of hours. With this many of us working at it, the sentries on watch won't suspect any single person.'

That made sense to them, and several nodded in agreement. Proceed to part two, Kendall told himself.

'This is the clever part. We drive north, to one of the Baby Bunkers. Already supplied with power and lighting and bedding and emergency supplies.'

Expressions of surprised acknowledgement from his audience.

'Now, everyone has spent time out at the Baby Bunkers on the rota system, but I managed to measure the dimensions of their entrance apertures. A Rapid Rider parked alongside will completely block the entrance so we'd be protected from any roving hostile plants or insects.'

The unspoken addendum was that Serendipity would be under vegetable siege from everything capable of movement on ZLM Prime, a giant decoy allowing them to seek refuge in safety.

'Now, I recommend that we start to get supplies aboard that Rider soon, so we can get away just before daylight. Okay?'

A muffled chorus of agreement broke out as the others slid chairs back across the floor.

For the next hour a seemingly random procession of those seven people made their way from the bunker and over to the small vehicle park, coming and going in ones or twos, until Kendall was satisfied that they'd stockpiled enough in the way of food and water. Standing in the unofficial rendezvous of the canteen, he looked around for Beatrice or her sister, didn't see either of them and waited until Arthur Dawson came past, returning from outside.

'Where've the Schoonmakers gone?' he asked. Both were easy on the eye, and would make splendid female slaves once he got that carbine.

'To the bathroom. Long journey ahead, been drinking lots of water. Can't exactly stop en route for a toilet break,' said Arthur, apologetically. His wife put in an appearance, looking nervous and shifty. Kendall sighed inwardly, worrying that the woman would give the game away with her lack of caution.

'Montag's left his induction pistol in the Biology Bay,' she whispered conspiratorially.

Might as well put up a sign saying "PLOTTING TAKING PLACE HERE" mused Kendall.

'Why didn't you take it?' he asked.

Vicki shrugged with distaste.

'Plabby guns! I'm not touching it! You brought it here, you can get hold of it.'

Not the plasma carbine, reflected Kendall. No, but if he got an induction pistol he could silently kill the sentry and get their weapon.

'Right, I'm going to get it,' he warned them. The Dawsons exchanged a look of mockery at his willingness to acquire a weapon. Well, let them! They were both expendable.

The Biology Bay was, next to the Specimen Bay, the furthest recess in the bunker, and it took Kendall a minute to get there. Before entering he looked around casually, careful not to look as if he was looking. Nobody watching, in fact most people were asleep.

He pushed through both sets of doors, finding the Bay empty of staff.

Excellent! he thought, smiling tightly. Where's that gun?

Five minutes later he felt less satisfied, having gone over the whole bay without finding the induction pistol.

'Missing something, fnorp?' asked a hostile voice.

Montag stood inside the inner doors, his induction pistol pointed forward.

Kendall felt a horrible jolt run down his insides, churning his stomach. That look of mockery the Dawsons shared with each other –

'Nothing!' he snarled, pushing past the other man, and managing a half-walk, half-run across the bunker floor to the exit ramp.

Arpad Szeged stood on sentry, looking inwardly, and pointed the deadly carbine at Kendall before he got anywhere near the exit ramp.

'Have the Dawsons gone?' asked Kendall, sweating chilly beads of brine.

'Them and the Schoonmakers. Swoozie and Friday Lockwood, too,' replied Arpad. 'Gone to help the Doctor get plant specimens.'

Kendall ground his teeth in blind anger. Fnorping plabby moojs! They'd taken his idea, then got him out of the way with that story about Montag and his gun and –

He jogged outside and witnessed that the second Rapid Rider had indeed gone.

Eric gathered his wits and shoved back, hard. The cargo, being empty plastic containers of ten gallons capacity, fell away from him and back into the bed of the vehicle, making a horrendously loud clattering.

'Everyone okay?' asked the Doctor, ingenuously.

'I'm alive,' scolded Rose. 'Scared stiff but alive.'

'I fought back valiantly against the plastic boxes and lived,' added Eric, to an amused snort from the Doctor.

'Human humour! Okay, voices are fine, talking is fine, since sound consists of low frequency oscillations. Light is much more dangerous.'

Eric could only make out the dimmest of surroundings in the pre-dawn gloom. No lights in this blackness?

As if in answer to his unspoken comment, a pale blue light began to issue from the driver's cab.

'Useful gadget, that,' he commented.

'Keep quiet,' countered the Doctor. 'Get those torches I asked for.' He dug a fire-extinguisher out of the cab, looped a cord into the handle and slung it over his shoulder.

When Eric switched the sturdy Chinese battery-powered torch on, he got a dull red glow that illuminated the nearby landscape in a weird, low-relief fashion.

The Doctor gave a low, impressed whistle, causing Eric to look at the stalled Rapid Rider.

A toppled Weepy Willow lay in front of the battered front grille of the tracked vehicle, knocked completely free of the soil by the force of impact. A few branches stirred feebly in the rays of the torch. Overall, the tree was at least ten feet tall, with it's branches adding that much again.

'Right. Sterile gloves on, lazy-tong scissors and tongs out, get the empty plastic boxes. Come on, hop to it, we haven't got all night!' scolded the Doctor. He carefully scanned a full circle, seeking any potential threat.

Nothing desperate. Kink bushes writhed slowly in clumps, and a few giant parasitised insects lumbered and stumbled mindlessly across the dark lands. Slow threshing in the background was made by Weepy Willows beyond eyesight.

Rose squeaked in fright, pointing at a silvery flash that darted at the trio, a fleet and sinister metallic minnow a foot above ground level, dorsal spines rippling in anticipation of shredding them apart.

Sillipede! No – Adapted Sillipede, recognised the Doctor, already levelling the sonic screwdriver and giving it eighty-five percent power. With a penetrating ping! the scuttling insect fell apart in mid-move, spines and scales shedding to all sides as the creature's internal organs collapsed into a tangled puddle of slime.

'Exoskeletal,' explained the Doctor, aloofly. 'Shatters apart under infrasonic attack.'

Slightly stunned, Eric paused to look at Rose, who shrugged and smiled wanly.

'Can we get on with pruning the roses?' she asked. The Doctor immediately became contrite and applied himself to the task at hand.

'That clump there,' he warned, walking slowly towards a Kink Bush. Rose and Eric opened several plastic boxes in preparation.

Using the lazy-tongs to stay safely away from the slowly wriggling tentacles, the Doctor severed one extruded seed-pod after another, then picked them up and dropped each into a plastic container. He put the lid back on, loosely, allowing Eric and Rose to secure them firmly and stack the boxes back in the Rapid Rider. Having pruned that particular Kink Bush into harmlessness, he swept the ground for another. A large, slow-moving hummock under the soil intervened.

'That's got to be a Big Bug,' observed Eric. 'They travel under the topsoil sometimes.'

With his usual curiosity, the Doctor gave the earthy carbuncle a prod with his lazy-tong scissors. The soil stopped moving, slowly becoming darker. After half a minute the movement began again, a large patch of damp soil being left behind, glinting faintly in the ruddy torchlight.

'Don't touch that,' warned the Doctor. 'Doubtless poison of some kind, fatal to the touch.'

'It's a bit of mud!' argued Eric.

'Mud contaminated with very high levels of toxic excretion.'

'Toxic?'

'Oh, yes! A defensive mechanism to keep hostile predators at bay.'

He pointed at surface grasses dampened by the liquid – without exception, they withered, blackened and died in seconds.

Abruptly, struck by yet another idea, the Doctor pursed his lips and stroked a non-existent moustache. He rapidly broke three branches from the now harmless Kink Bush and used these to pin the sub-surface Big Bug in place. What was it that Rose had mentioned?

'Do we have enough?' asked Rose, feeling that they did, and that she didn't want to go strolling across this nightmare landscape any longer than she had to. Beyond the range of torchlight the night was noisy and sinister, full of muted sounds made by things she really didn't want to see.

'Nowhere near. We need plenty more. However, moving around is going to get more and more dangerous the closer we get to dawn, so I want to stay close to the Rider. See any more Kink Bushes?'

The nearest para-intelligent parasite bush stood in a clump near a small copse of Razor Trees, those arboreal giants with the strangely level tops. Normally the trees swarmed with Faterpillars and the occasional feeble Tree Crawler; now they stood stark and silent, ruddy dark giants in the inadequate torchlight.

Once again they began to harvest extruded seed pods, rapidly acquiring dozens from that particularly fruitful clump. The work was nerve-wracking but without incident for over ten minutes. At that point ZLM Prime revealed how dangerous it could be.

Rose, keen of eye and nervous of mind, spotted it first: a long, disturbingly animated mass moving into the Razor Trees on the side opposite them. She clutched the Doctor's arm and pointed wordlessly.

Readying his fire-extinguisher, the Doctor moved slowly in front of Rose. The mobile horror slowly revealed itself to be a Faterpillar in the final stages of parasitisation, a mere mass of tentacles barely able to put one leg in front of the other.

The hideous tentacled hybrid moved beneath the branches of the Razor Trees on a course that would lead to them, at which point fate took a hand. From the branches of the tree directly above the Faterpillar a madly threshing bundle of legs and fangs pounced, driving it's teeth into the hybrid so fiercely that all three heard the cabbage-like scrunch. Rose watched, aghast, as the Tree Crawler began to swell to the size of a football with all the body fluids sucked from it's victim. Any green tentacle that came near the Crawler was instantly hacked apart by the latter's claws, claws that moved faster than the eye could detect. After a wait of perhaps half a minute, the Tree Crawler dropped from the Faterpillar and dragged it's swollen body off into the shelter of the Razor Trees.

Admiring this display of nature in the raw, the Doctor was disturbed by the sound of Eric being violently sick, and the sight of Rose as pale as paper.

'Ah – best look away now,' he warned them gently. 'It's not over.'

The mangled and stricken Faterpillar lurched and staggered away from the three travellers, over to the copse's edge, where a Weepy Willow stood – or, more accurately, slowly danced. The hybrid ran right into the tree-trunk. Before it got a chance to back off, long willow branches came snaking out of the night, ensnaring the Faterpillar and lifting it clear of the ground. The dying creature was lifted over the centre of the tree-trunk, which dilated open into an enormous pink-fringed maw. Seconds later the Faterpillar was no more than a bulge in the circumference of the tree.

'Time to leave, I think. Do we have any chains in that Rider's tool locker?' asked the Doctor of Eric, who shrugged, busy looking miserable.

'Yes,' answered Rose, who had nosied through the accessory bins as a matter of course.

'Good.'

Traditionally, cheats never prosper. Arthur Dawson had to keep reminding himself of this as the Rapid Rider went bulleting into and out of the gap cut in the Dyke.

He grinned to himself, pleased that he and the other five had successfully duped Kellerman into getting left behind. Cheating a cheat didn't count, he decided. Arpad had been easy to fool – getting more specimens for the Doctor's defence, they'd said, and needed six staff to get as many as possible as quickly as possible. He'd even wished them good luck.

Now they were free. Nip up to the eastern Baby Bunker, park up, off-load the supplies, sit out the horrible creature-siege of Serendipity. Simple. Arthur had managed to convince himself that they were doing the mission a service, in case the main bunker got overrun by insane plant-creatures. If that happened then at least a small group of them would survive.

Dim and distant, a narrow arc of red glowed across the horizon as ZLM began to slowly rise.

Great! enthused Arthur. That'll make driving easier. He still kept the headlights on full-beam, not wanting to collide with anything. Thanks to the extra illumination he could see the semi-circle of plants and plant-infested creatures lying in wait, a big curving formation.

'Hold on, shrubbery to drive across. Might be a bump or two,' he warned, dialling the gears down.

With a few bumps, the Rider drove over the assmbled greenery, crushing a great swathe across it and into the ground beyond. They suffered a loud smack as an unseen opponent hit the cab door, but that was it for hostile action.

On they trundled, with dawn coming slowly. Strangely, the amount of hostile plants or parasitised creatures didn't seem to diminish as they put more distance between themselves and Serendipity.

'You know, I think they're making directly for us,' commented Swoozie in the rear, uncomfortably settled on a pallet of water blivets.

'Rubbish!' scolded Vicki, only to nearly jump out of her seat at the sound of dozens of objects striking her side of the with great force.

'What was that?' scowled Arthur. Nobody knew; it was still too poorly-lit outside to tell. He detoured to avoid a copse of Razor Trees, where the ground beneath the spreading branches lay littered with dessicated insectile bodies. Whatever did that, they didn't want to meet.

By the time they got to Baby Bunker East, the sun had risen a hands-breadth above the horizon, and the day had truly begun. Arthur drove alongside the bunker entrance with considerable care, blocking off any access except for that via the Rider's right-hand cab door. They opened it, and clambered out one at a time, forming a chain to move supplies into the top level of the bunker. Dirt and debris had been blown into the structure, neglected for an unusually long time thanks to the flare-up. Up here on the upper level the daylight helped to disperse any imminent feelings of gloom. Arthur went down to the lower level with a torch, which he needed in order to avoid falling off the ramp edge or tripping over any of the cables laid on the floor. He found a bank of lights and set them going, then started the back-up generator to charge the batteries. All the time he swept his torch beam back and forth, seeking to pick out any sinister alien attacker or intruder before they got to him.

Beatrice caught a bundle of water blivets and felt a sudden series of tugs around her ankles, followed by sharp pains digging into her ankles and shins. Simultaneously, a series of sharp, stacatto noises came from the far side of the Rapid Rider, as if stones were being thrown at the vehicle.

'I've been – bitten, I think,' she gasped, dropping the blivets and pulling her boilersuit trouser cuff upwards, dislodging several long spines that had sunk into her skin.

'AH!' she gasped, as hot, agonising pains ran up her legs from the ankles, where blotchy red weals showed up in contrast against her pale skin. Her sister came over at a run, as Beatrice felt her legs give way. Juni saw the red weals spread into the veins of her sister's leg with incredible speed.

'It hurts!' shrieked Beatrice, eyes wide with fright and pain. 'Make it stop!' She began to thrash around.

The others stood around helplessly. They didn't even have a first aid kit to hand.

Juni tried to hold her sister down, mumbling reassuring nothings whilst looking almost as panicked herself. Beatrice gave a last howl of anguish, clutched her chest and fell back onto the dirty floor, dead.

'What – happened?' asked a shocked Juni. Arthur spotted the long, thin spines that had come loose from Beatrice's boilersuit. He carefully picked one up using a sheet of plastic, noting that the spine was hollow, a clear sap still partially filling it.

'Kakti spines,' he deduced, in a subdued tone. 'They must fill up with poison. And the cactus can fire them like arrows. Stay away from the entrance!' he suddenly barked. That would explain the feeble pre-flare up performance of the Kakti. The plant only became dangerous when it boosted it's energy, and added poisonous sap to the shooting spines.

The group looked around each other.

'There's still stuff in the Rider,' said Vicki. 'Food and water.'

'Leave it,' stated Swoozie. 'If we need it we can work out how to get to it, later.'

They covered Beatrice's body with a tarpaulin, weighted the corners down with rocks and carried supplies down into the lower level of the bunker without speaking. A funereal atmosphere followed them, not dispersed at all by turning on the banks of floodlights that lit the lower level up with a merciless light.

'It wasn't supposed to be like this. Not with anyone dying. 'Specially not my big sister,' sniffed Juni. She sat clumsily on the edge of a bunk bed, which tipped up and nearly threw her onto the floor. 'This was supposed to be safe.'

Arthur felt her accusing eyes burning into him. He felt that, whether it happened or not.

'Don't look at me like that!' he snapped.

'It's not your fault,' whispered Juni. 'Really, it's not. It's this planet. And The Administration. We should have been – they should have sent – a proper expedition.'

Vicki, about to jump in verbally to defend her husband, stopped before speaking, ashamed that the teenaged girl had been so forgiving.

'You're right,' she added. 'All this – we're amateurs. Amateurs doing the jobs of professionals. They should have sent proper astronomers, and geologists, and botanists, instead of us. The rejects and the retreads.'

For an instant, a second, all five felt a common bond, a connection, and felt united.

It only lasted until they heard, and felt, the first thudding impact against the bunker walls, a muted impact like a subdued drum-roll. Dust and flakes of fusor-laminated bunker wall drifted to the floor all around.

'What the fnorp was that!' gasped Swoozie. A second and more forceful impact hit one of the walls, physically transmitting a shudder into everyone listening and bringing more dust down from the roof.

Arthur glanced around the whole bunker, wishing he was more skilled in geology than astronomy. A working knowledge of the behaviour of quasars in this situation didn't count for much –

'The generator!' he realised, pointing at it just as Monday Lockwood did. To jump across the vault and turn off the plant took seconds.

Sub-sonic broadcasts, realised Arthur. The generator stood firmly on the bunker floor, which meant any vibration it created would be transmitted to the outside subterranean world, an irresistible invitation to any adapted ZLM Prime wildlife. Nobody knew what creatures dwelt in the depths of the soil here – no staff to research, no time to spare, no equipment to scan –

'Great,' came the acid voice of his wife. 'Now we sit here in darkness - '

'Shut up!' hissed Arthur. 'Noise travels. Whatever's out there is homing in on our noise. So shut up!'

Five minutes of silence convinced one and all that the generator had been the problem. The battery would allow their light bank to operate for hours before it needed charging. But, eventually – it would need charging. There were no more attacks on the bunker walls, not so long as they remained silent. Swoozie found a scrap of paper and a fragment of carbon, scribbled a note and passed it to Arthur. He read it:

"Why not go back up – daylite + supplies"

Because of the body lying up there, he morosely told himself.

"Kakti plant in ambush" he scrawled, laboriously. "body".

Swoozie rolled her eyes, picked up another piece of paper and dropped the carbon in fright as a terrific high-pitched crack echoed around the chamber. Arthur saw a spray of fine dust arc out from one wall, and a hairline fissure appear from roof to floor in less than half a second.

Moving from her position on the camp bed, Friday Lockwood tapped his shoulder and pointed upwards, indicating the upper level.

Fair enough, thought Arthur. Another crack sounded, and more dust jetted into the chamber.

'Let's get upstairs,' he whispered. The five began to gingerly move away from the scattered equipment, towards the slanted access ramp at the chamber's rear. Another staccato crack became a sudden chorus of variously-pitched shattering sounds, and a giant panel of the bunker's lower wall suddenly collapsed inwards, bringing with it a non-stop flood of earth.

Dragging Vicki along by main force, Arthur didn't stop to look behind himself as a tidal wave of mud, roots, tentacles and fusor panels began to fill the lower level. He bounced off the corner and made it to the top of the ramp, gasping for breath in a combination of both exertion and fright.

Swoozie and Juni looked at him, then back at the huge mound of earth that nearly filled the lower level.

'Friday tripped on a cable,' whispered Swoozie. 'She got crushed by that.'

'What did it?' asked Vicki, in a quavering voice.

Arthur motioned them up the ramp.

'Something big we don't want to meet again.'

Nothing like this had ever, ever happened at Serendipity. Mind you, the walls there were immensely thick. Vibrations wouldn't get transmitted through them, and predatory soil-dwellers wouldn't be able to smash them.

Arthur risked a quick glimpse out of the bunker entrance and witnessed a living wall of hostile plant-life now arranged on the other side of the Rider.

Waiting.

FIFTEEN

By the time the Doctor proudly drove his Rapid Rider towards Serendipity base, a flush of red in the sky warned of dawn approaching, and a vague light began to spill over the landscape.

'We need to get cracking, once the sun's up it'll ginger our little friends into becoming much more active,' warned the driver.

'Photosynthesis?' guessed Rose, correctly. She didn't like being right, since the barrier of hostile plants had been unpleasantly active already, despite it being fairly dark still.

'Where are you going to put that thing?' asked Eric, indicating their towed burden. Their major towed burden, anyway. A couple of the minor towed burdens had come astray in the increasingly dense ring of plant and hybridised creatures now encircling the base.

'Right here,' beamed the Doctor. 'To fill the gap in your siege wall.'

He stopped just short of the entranceway cut into the Defensive Dyke, jumped from the Rider and began to dig a hole, using his hands at first and then using a spade that Rose handed him.

'Sloping on this side, sheer on that side,' he observed, piling loose soil around the rim.

Eric watched with curiosity, wondering how the stranger was going to plant the Weepy Willow in that hole – the branches were beginning to thresh around now that daylight was near.

Using very low gearing, the Doctor carefully dragged the tree by its chain until the rootball slid into down the shallow inslope and hit the sheer wall. Slowly, it was dragged upright as the Rider moved forward and pulled on the chain, loosely-piled soil falling onto the roots. Finally the Doctor released the chain and drove away, leaving a writhing sentinel at the one extant breach in the Dyke.

Next, he carefully parked well away from the anti-erosion netting due to the nature of their lesser towed burdens.

'Eric – I need to set up a supporting framework for these captives. Can you bring along any small-bore piping and plastic sheeting that you can find? Rose, I need a pair of heavy duty gloves, and a pint cup.'

When the two returned, they brought not only the supplies he'd asked for, but a few anxious observers, too. Without bothering to inform anyone exactly what he was doing, the Doctor knocked pipes into the ground, tied other piping horizontally, draped plastic sheeting and generally tinkered.

Arpad was the principal amongst the observers, witnessing the half-dozen Big Bugs that the trio had brought back from their excursion, giant insects bound with chains and exhibiting signs of scuffing and scratching after being towed behind the Rapid Rider.

'Don't touch them!' warned the Doctor. 'They're giving off a contact poison.' He ignored his own advice, thanks to the gloves Rose had brought, and hefted one of the enormous beetles, twirled it upside down and set it on the pipe framework. Unable to right itself, and in a condition of stress, the beetle began to excrete poison, which dripped down onto the plastic, then ran down the plastic and into a depression in the centre. The Doctor put the pint mug underneath the plastic and swiftly created a hole with his sonic screwdriver, allowing the poison to collect in the cup.

'Bravo!' applauded Arpad, still mystified, watching the Doctor repeat this process for the other Big Bugs. 'What use is your poison-collector, Doctor Smith?'

'Not a bad improv, if I say so myself,' mumbled the Doctor to himself. 'Adaptation of the old dew-collector principle. Eh? What use?'

'Weedkiller!' realised Rose. The Doctor winked at her.

'Just so. This lot - ' and he swept his hand over the entire Serendipity compound 'have no idea what a weed is. All the harvestable crops on Earth are genetically-engineered and weeds are extinct. It was your aside about "paraquat" that got me thinking, Rose.'

Rose basked in the reflected glory of inspiring her mentor.

'Now – Arpad, can you dilute this collected toxin? I want it taken down on a ratio of about ten to one.'

Lev, out to get fresh air and satisfy a sense of curiosity, put his hand up.

'Why not test how effective it is, vary the ratio you dilute it to? We've got plant samples we can zap test with it. Make it go further.'

The Doctor snapped his fingers and pointed at Lev, who recoiled slightly.

'I like it! Intelligent anticipation! Get to it!'

It fell to Dan to cause the minor commotion long in waiting.

'If you've dug that dancing tree in at the entrance, how are the others going to get back in?'

Rose exchanged a look with the Doctor.

'Others?' they both asked, simultaneously.

'You sent them off to get more specimens,' explained Dan, slowly, looking back and forth between the two listeners and becoming aware that his explanation wasn't really persuading them. 'In the other Rapid Rider. Remember?'

The Doctor shook his head decisively.

'Uh-uh. No I didn't.'

Dan, and others paying attention to him, looked worried.

'What were they doing?'

Casting his eyes to the heavens, the Doctor glared at Dan.

'Lying and stealing your Rapid Rider!' He balled his fists in anger at the selfish, short-sighted behaviour of these human absconders. Doubtless having taken volumes of supplies from the camp's stores, when the larger population here needed those very same supplies earnestly. 'Has anyone tried calling them on the wrist-phone?'

'Roj tried,'said Dan. 'No reply. He thought they might be too far away to pick up the signal.'

Sighing hugely, the Doctor mentally consigned those vanished to the infernal regions and concentrated on the here and now.

'Enough of that. We brought back a cargo of Kink Bush seed pods, all green and twitchy. They need weaving into that netting up on the Dyke.'

It was at this point that even the most obtuse member of the mission finally understood that phrase about fighting fire with fire: using lazy tongs and heavy duty gloves, the mission members crocheted separate Kink Bush seed pods into the protective nylon wall, creating a narrow band of living defences.

Lev reported back to the Doctor, and Roj, who now hung around the stranger with a put-upon expression.

'We can derive about five gallons of poison from one pint of the original, Doctor, at a concentration where it still kills plants almost instantly. And those Big Bugs are still pumping out poison. We stand to get hundreds of gallons if they keep up.'

A twinge of compassion stirred in the Time Lord.

'Better turn them right way up for a little while. Let them get their hideous insectile breath back.'

Now, the problem about their poisonous weedkiller was making sure it didn't evapourate in the arid atmosphere. Merely spraying over any attackers would be severely wasteful. Perhaps – perhaps making a solid derivative would serve better.

'Could you perhaps produce a granular base that can hold and retain the toxin?' he asked Lev, who scratched his head. 'So we can place it on the ground.' Lev made an 'ah' of enlightenment.

Well, congratulated the Doctor, rubbing his hands together. Things are working fairly well. Not too much to worry about. Apart from the so-far undiscovered Rutan spy and killer, and the half-dozen people stranded out at an unknown destination, and the imminent assault, and their inability to call for help. Yes, things were merely awful instead of hopeless!

Back in the bunker, Roj chewed savagely on the end of a writing-stick and cursed the half-dozen staff who decided to steal supplies and water and a Rapid Rider. He had already decided that the two tracked vehicles and Sun Gun One would be a last refuge for the mission members, if the perimeter was breached by a mass of semi-intelligent angry plants. And now one of the fastest vehicles they had was missing!

A shadow fell across his desk, making him jump in alarm, realising that he'd not been sitting in company, not even with a TESTer to sit as a sentry, and was thus entirely vulnerable to the Rutan spy.

The shadow turned out to be cast by Thijs and Katje Pierson. Roj relaxed; two people meant that if one was the Rutan, it wouldn't dare attack.

'Yes?' he asked, shortly. He still hadn't forgotten that their laxness had allowed Doctor Delgerd to walk into the jaws of death.

Neither, it transpired, had Thijs. He brought up into view a long length of scaffolding and for a second Roj thought he was going to be attacked with a piece of plastic piping.

Instead, Thijs held the pipe up vertically, looking into the bottom.

'It's a periscope,' he said, indicating the viewing gap cut into the bottom section. 'I used blank CCD's as the mirrors.'

Roj tried the device whilst sitting down and could easily see over the cubicle walls. He turned on his wrist-phone.

'Dan! Stop flirting with Wodie Wolff!' he snapped. Dan, sitting at a table in the canteen area and leaning close to Arkan's wife, jerked upright in alarm and looked around in amazement.

'So we can see over that nylon web wall,' added Thijs. 'With all the Kink Bush seed pods stuck in it, you don't really want to get too close.'

'Can you make a few more?' asked Roj. His wife came into the cubicle, directing frosty looks at the Piersons, and carrying a selection of flavoured soya chunks for an early lunch.

'Those plant things are beginning to move,' she warned. 'Not a lot, but definitely moving. It looks like the circle they made is shrinking.'

The flesh on Roj's back crept coldly at this news.

'More periscopes, please,' he ordered.

Thijs hesitated before leaving.

'What do you want!' asked Christy, in what might be described as a "terse" tone.

'My specialism's neurology, not botany. Still, even I know that plants need photosynthesis to keep functioning.'

Roj frowned. As an astronomer, botany was even further from his field of expertise. What was Thijs after?

'They need sunlight to photosynthesize. If we created a low-level cloud that blocked out the sun's rays, then they'd return to being sluggish and inert. The reason that they're beginning to stir now is the presence of sunlight.'

'Block out the sun!' scoffed Christy. 'With what!

'

'Shhh!' said Roj, most untypically. The sheer unusualness of the abrupt command stopped Christy in mid-sentence.

With what? They'd have to improvise. Something that the fnorping Doctor didn't come up with out of the blue to challenge him for leadership.

'Get on it after you make a couple more periscopes. Use anything you need to, and refer anyone who complains back to me.'

The biologists departed, followed by Christy's unkind gaze.

'Roj – are you really giving those two plabbies a free hand? Is that a good idea?'

He smacked the desk top with a large (if flabby) fist.

'Snelf, Christy! We all stand to die horribly if we can't stand off those hordes of things lying in wait for us out there. Any idea is a good idea at the moment. We are eight hundred and fifty light years from any possible help, you know, which rather casts us upon our own resources.'

Christy, wise wife that she was, avoided pointing out to her husband that there were human colonies in star systems closer to ZLM than Earth.

Rose went for a shower. It was one of the few luxuries available to the mission staff and she needed it after the horrible night work she'd done, followed by the grind of the dawn work she'd done, and looking after giant poison-dripping beetles. According to the Doctor, here in the showers they were safe from the Rutan; something about water and electricity that she hadn't followed too closely.

Damn, but being an intergalactic rover could be hard work at times! she reflected, towelling off before getting a fresh boilersuit from the clean laundry hamper in a corner. That was when she noticed the pack moving slightly, a gentle rocking motion.

Instantly she backed away, remembering nasty surprises at the lift-shaft. The rocking motion stopped and a muffled noise came from the hamper.

'Hello?' she ventured. The hamper rocked again, and the muffled noise came louder. Gingerly, Rose tiptoed over to the hamper and lifted up a corner of the assorted towels and boilersuits.

A red-rimmed eye looked back at her.

Rose yelped in surprise and dropped the fabrics back, before realising that she'd seen a human eye. Reaching into the hamper, she lifted a whole layer of laundry clear, revealing Davinia Szeged, who had a bad cut over her left eye, with a bruised purple background over that side of her head.

Swiftly, if a little ungently, Rose tipped the injured woman out of the basket.

Davinia groaned and clutched her neck, then rubbing the back of her head

'What happened?'

Davinia looked at her wrist-phone, the dial smashed and dark, then up at Rose.

'Somebody hit me from behind. And - ' she glanced around ' – they took my pistol.'

Then they hid you, pondered Rose. To prevent anyone from discovering you quickly. But they left you alive. Wonder why?

'Come on!' she announced, helping the older woman to her feet. 'Let's get you sat down and wrapped around a cuppa.'

They managed to get out into the canteen area, where curious and helpful staff took over and helped Davinia. Rose decided to inform the Doctor and left the bunker in a hurry, emerging out of the air-conditioned cool and instantly acquiring a layer of sweat and airborne grime.

Before she could track down the Doctor and his peculiar horticultural expedition, one of the TEST rats popped up almost under her feet.

'!' it signalled, ducking down in the fashion they had when scared.

Number 3, realised Rose. The giant rodent gestured in a near-human way with one paw and led her away from the bunker and towards the Rapid Rider, turning to cup a paw over it's mouth and pointing to her as well.

Stay quiet? mouthed Rose. Number 3 nodded, in a gesture amazingly close to human. As she followed it stealthily padded closer to the tracked vehicle, before lying prone and pointing underneath.

Rose wrinkled her nose at the sight of a dead rat. Then she caught sight of Number 3, which sat upright looking at it's dead compatriot, both front paws clasping and unclasping.

'Mate,' it signalled to Rose, who felt as if she'd been punched in the stomach at this revelation. Her stomach flipped again when she realised that the rat had been shot.

Who here was enough of a bastard to shoot rats on sight? And who wanted a gun but had been deprived of one? And who did she dislike enough to believe the worst of?

Kellerman! she hissed. On cue, a pair of boots moved out of shadow and into view beyond the Rapid Rider, against the scuffed plastic hull of – what did they call it? – the Sun Gun.

Immediately suspicious, she should have simply gone to get help. Instead Rose decided to see who was actually sneaking around between the two expedition vehicles. If it was simply a staff member refuelling then she'd look pretty sick explaining to anyone who came running to help her.

Besides, the yard-long solid steel torsion rod she unpinned from the Rapid Rider gave her enough confidence to face down Kellerman if she caught him up to no good. The rod ended in a big heavy socket that would put a perfect dent into Mister Gitfinger's skull if she caught him at it –

However, when she crept between the vehicles there was nobody there, and only ruffled nylon anti-erosion netting showed where there had been anyone present.

'Bum!' she said, with feeling. Okay, so whoever it was had moved on. What had they been doing with the Sun Gun?

The big cargo hatch on the rear decking was open, inviting a look inside, so Rose tiptoed over the netting and stood up to look in.

Water bottles, tins of food, a couple of fire-extinguishers –

A slight scrape on the netting behind her alerted Rose, too late to avoid the tremendous blow that felt as if her head was coming off and delivered her into darkness –

Kellerman pitched the body into the cargo space and slammed the hatch closed. Just his luck! First one of the rats got nosey, and now that damned assistant to the alien Doctor. His first instinct had been to shoot her dead, before he reconsidered and decided that a bit of intimate female company in the wilderness would be quite pleasant, and she'd make a fair hostage to boot. Given his skills in covert operation, she'd never even seen him before he knocked her senseless. Amateurs! Who needed them!

Time was still important. That bitch Davinia might well implicate him even if she'd never seen the attack coming, and she wouldn't stay stuck in the laundry forever. A shame there were limited rounds for the induction pistol, he'd love to have given her one between her vapid eyes.

Partially concealed from view by the one-way exterior coating, he slid into the cockpit, cranked the hatch down and inspected the control panel before switching it on. Green lights all around. The pocket power plant hit optimal within seconds and he grasped the Sin and Dex control handles before flooring the acceleration pedal.

Slowly at first, before gaining speed, Sun Gun One slid over the floor of the base and picked up speed as it crossed the Dyke, hitting a section of the nylon netting and tearing it loose. The abrupt descent down the steep outer slope forced Kellerman to jink left and right to avoid losing airlift. He grinned an unpleasant grin at the thought of the hostage being thrown around in the cargo hold.

'Doctor!' came a shout from far away.

The Doctor immediately awoke, cast around, fixed himself and the helpers in place on a mental map, found no immediate danger –

'What are they doing!' he yelped, seeing the hovercraft Sun Gun One fly through a section of protective walling, knocking a good ten metres away as it smashed past. It took half an hour to resurrect the protective wall, time enough for the Piersons to finish their periscopes and determine that, yes, the ring of hostile plant life was closing in on them, slowly.

Much as he was dismayed and puzzled, Roj was positively apopleptic when informed. Another vehicle stolen! That only left the bulldozer, which managed five miles per hour on a good day, and the heavy loaders, which barely moved faster than a walking man, and which were also entirely open. No way could anyone escape on those!

'Fire extinguishers,'said the Doctor, snapping his fingers whilst watching Thijs and Katje Pierson fumble around with pipes. 'How many are there?'

Eric was closest and heard the intonation.

'Not enough. We didn't come expecting to fight fires on a daily basis.'

Murray and Rogan sauntered out to the dirty, sweaty, tired fence-erectors with trayfuls of chilled water blivets.

'I believe Roj has discovered Kellerman is missing,' said Murray, handing out the blivets to eager hands.

'Oh? So he stole the hovercraft,' interpolated the Doctor. 'Frankly we're better off without him. He didn't persuade anyone else to go with him, did he?'

Murray shook his head.

'From what I gather, the others who disappeared earlier were the ones he convinced to leave here. I'd rather take my chances here with you lot than be out there with that mooj.'

The Doctor gave him a grateful smile. The ring of silent, implacable besiegers had visibly contracted in the past hour, thanks to the energy boost of sunlight. Murray's brave words would be tested soon, and at length.

Thijs and Kaatje were now poking around the Rapid Rider's engine mounting, having seemingly abandoned their pipe-wrangling. The Doctor observed Thijs place a handful of litter on the Rider's cab roof, then set light to it.

Peculiar! Working to some end, that they know not of.

Two TEST rats came to investigate the party, pausing to check the identity of everyone present, before scampering off again. Nobody paid any attention to this at the time.

'Five,' stated a grouchy Eric, throwing himself down on the nylon netting alongside the Doctor.

'Alive, Famous or Dave Clark?' replied the Doctor.

'Fire extinguishers. There are only five. There ought to be at least a dozen.'

Another logistic casualty of the parties now departed.

The Doctor looked across to the far side of the base, where Thijs and Kaatje were returning from scrounging around in pallets. They carried what looked at first like a sleeping snake, until they got closer and the "snake" turned out to be a long piece of flexible plastic piping.

'Eureka!' exclaimed the Time Lord, as pieces from an invisible mental jigsaw fell into place.

'Pardon?' asked at least three members of the fencing group.

'Sorry, forgot, moment of enthusiasm. Greek not spoken any more, eh? It means I've got it, when I didn't realise I needed it in the first place.'

Glances amongst his audience proved that the Doctor was indeed the only person who knew what he was talking about.

'You lot can do what you want to now, I'm going to see Roj.'

The marked drop in temperature once he crossed into the Bunker made his step considerably lighter; air-conditioning plant, big , fusion-powered, and flexible piping. Couldn't be simpler!

Except that real life intervened before he finished explaining to Roj.

'Think about how the fire extinguisher affected the Kink Bush.'

Mute nod from Roj.

'Now, imagine a fire extinguisher that's only cool, not sub-zero.'

Another wary nod from Roj.

'But – and this is the kicker – this fire extinguisher never runs out.'

Before either man could continue, two TESTers ran into the cubicle past Montag at the entranceway.

"!" they both signalled. "3 gone" indicated one, and "GoodRose gone" indicated the other.

Roj looked up from the rodents to stare at the Doctor.

'Have you seen your little friend around, Doctor?' he began, addressing the empty air as the other man whirled away and sprinted to Rose's cubicle.

Empty.

'Rose!' he bellowed, to a faint echo but no answer.

Things had not gone smoothly for Kellerman. Firstly, he wasn't experienced at handling a hovercraft, which meant several sidelong skids that threatened to pitch the whole vehicle over. Secondly, he'd tried to burn a way past the encroaching monsters with the aerial arrays switched to Transmit instead of Receive, anticipating that the microwave radiation would repel if not destroy the hideous hybrid creatures.

Instead, they'd flocked to Sun Gun like bees to honey and forced him to kick the emergency boost button that sent them soaring fifty feet into the air with no guarantee where they'd touch down.

Fortune smiled briefly on him and the hovercraft hit ground well beyond the ring of plants, denting the bow skirts.

His intention after that was to make for water and cross it, to avoid any more insane plants that wanted to drink his blood, so he headed due north, for the nearest beach. At least, until he heard the strange sound coming from the cargo bay.

On stopping the hovercraft, he carefully went outside and opened up the cargo bay deck door to see Rose, awake and battered, sitting in a slurry of burst water blivets and shattered food containers.

'My supplies!' he shouted, pulling the induction pistol free from his boilersuit pocket.

'What do you expect, you numpty!' snarled Rose in reply. 'Driving like a boy racer on his eighteenth!'

The allusion was lost on Kellerman, who ordered her out of the mess and into the cockpit, where he felt better able to keep an eye on her.

'Any funny business and I'll shoot you,' he warned.

Yeah you would too and all – 'Okay,' she replied, mildly, concentrating on the horrible ache in her neck.

Once again, bad luck struck Kellerman. Only minutes after starting again, the hovercraft engine began to run erratically, making strange whooping noises interspersed with unpleasant grating. The vehicle's air-cushion began to fail, as indicated in a bank of tell-tales at Kellerman's side.

'Oh dear,' he intoned, smiling his unpleasant non-comic smile. 'Looks like we're losing the air cushion.'

They skirted a large copse, to see twinkling wavetops marching back to the next landmasss ten miles distant.

Kellerman slowed Sun Gun, feeling the increased drag from a less effective ground-effect. Driving one-handed, he cranked the cockpit open before producing his gun and levelling it at Rose.

'Going to shoot me, are you?' she snapped, proudly. 'So much for your hostage.' The only thing she had on herself as a possible weapon was a biro, and she'd never make the distance between them to jam it in his nasty squinty eye –

'I won't need you when the relief ship arrives,' he told her. 'You or anybody else. At the moment you're just deadweight.' This seemed to amuse him, and the smile became more intense.'Deadweight,' he repeated, adding more power to the uptake and getting ready to shoot.

'You see, Rose, I need to get over there - ' gesture with induction pistol at distant land ' – and since the Sun Gun is suffering, it's not going to be able to take the two of us all that way. No. It'll sink before we get there. So I'm going to kill you and reduce my overall mass.'

He levelled the gun at her, smiling his non-smile over the gun barrel.

SIXTEEN

A pair of the TEST rats accompanied the Doctor into Rose's cubicle, so he sent them outside to look for the young woman whilst he looked inside – to no avail.

A good five minutes of scouring the bunker failed to reveal any trace of Rose, and the last person to see her was Davinia, recovering from being attacked by an unknown assailant.

'Kellerman,' deduced the Doctor, before the injured woman could even open her mouth. A nasty apprehensive feeling encroached on his consciousness. 'Kellerman. Who stole the hovercraft.'

The two rats came scampering back inside, to a piercing glare from the Doctor.

'Has Rose been taken by Kellerman!' he barked, making them both quail. 'Sorry. Just a bit wound up.'

Both rats nodded and signalled "Yes", which meant a few staff heard an interesting number of quaint Gallifreyan phrases that would not have translated very well into polite English.

Worse was to come: when the Doctor raced outside to take the second Rapid Rider, he found the cab dismantled and the engine removed.

'What - !' he managed, bewildered, pointing at the engine. Both Piersons had gone back to wrangling pipes again, and had attached the flexible plastic tubing he'd seen them with before, to the engine. Why they wanted to marry plastic pipe to the hulking power unit for a tractor he didn't know.

'Yes?' replied Thijs, slowly.

'Can you put it back?' asked the Doctor in a strangled voice.

'Back?'

'Yes, back! You know, back into the tractor where it ought to be in the first place!'

Thijs frowned.

'Not easily. Nor quickly. Given an hour or two I suppose we - '

The Doctor groaned in dismay the moment he heard "hour". He needed to track down Rose and rescue her, just when the mission needed his help in dealing with the approaching hybrid threat: he didn't have any time to spare, let alone an hour.

'If you want a drive, there's always the bulldozer,' offered Kaatje, in what she

hoped was a helpful tone.

'I want a fast ride.'

Several people had followed the Doctor out of the bunker, impelled by his obvious anxiety about Rose's fate, or over the young woman herself.

'You could remove the dozer blade,' suggested Prentiss Deerfield, leaning against the no-longer Rapid Rider. Agreement and offers of help came from the small group.

Abruptly, the Doctor realised he could try to get the other Rapid Rider back and use that to pursue the kidnapper.

'Done!' he said, dashing over to the bulldozer. His volunteer helpers came to help.

'You'll need a couple of wrenches, and lubricant, and a hammer - ' began Prentiss, before the Doctor unleashed his sonic screwdriver on the connecting bolts that held the massive blade onto the body of the vehicle. Five seconds on the right, five seconds on the left and the group manhandled the blade away from the body of the tractor. The Doctor got rid of the towing assembly, then the mudguards and raced back into the bunker before returning with a small plastic reagent bottle from the Biology Bay. He hunted down the cover for the fuel tank, opened it and emptied the bottle's contents in, standing back in satisfaction.

'Want a hand?' asked Prentiss. 'I bet you've never driven one of these before.'

Not one of these, ruminated the Doctor. A T-34 once, and a Chieftan occasionally, but not a forty-second century bulldozer.

'Go on,' he replied cheerily. 'I'll watch you.'

There was room in the cramped cab for the two of them and nobody else. The cab stayed, since they'd be travelling past all those writhing semi-sentient attackers and needed protection.

When Prentiss gunned the engine, vast plumes of blue smoke shot from the exhaust pipes and the dozer surged forwards, causing onlookers to jump aside.

'What was in that bottle!' asked Prentiss. 'We're doing nearly thirty miles an hour!'

'Watch out for the Weepy Willow - ' warned the Doctor. The mobile tree did lash at them, ineffectively given their speed and the stoutness of the cab walls. 'The bottle? Call it an accelerator. It'll burn the engine out in an hour or two. By then …' an he let the sentence tail off.

Part of the silence was the sheer impressiveness of the encroaching wall of greenery they were approaching: every form of life on ZLM Prime appeared to have been parasitised by the Kink Bushes, and it was all moving closer to the Dyke. Even as they watched a conglomeration of walking tentacles that might have been a Weepy Willow began to drag itself forward, a flock of parasitised Faterpillars following.

Prentiss punched buttons and the dozer sped up even further, rocking alarmingly and smashing into the approaching host with a muted crunch. Variations on this noise sounded beneath the tracks as the massive vehicle crushed a path through the attackers, those at the rear of the circle having time enough to get out of the way. During every second of this progress a sleet of tentacles whipped and lashed at the cab, streaking it with slimy green sap.

'Any windscreen wipers?' asked the Doctor.

Rather than replying, Prentiss pressed another button, causing a slight shock to go through the Doctor, the backwash of a static delivery that cleared the cab entirely of the obstructing goo.

This allowed them to clearly see an extremely aggressive Sillipede, not infested by Kink Bush but still bristling with arrays of spines, that decided to throw itself at the translucent cab front. The Doctor gave it a quick blast from his sonic screwdriver, a blast slightly diffused by the cab's clear aluminium but still strong enough to make the giant insect throw itself from the engine to the ground.

'I'll head for the nearer Baby Bunker,' said Prentiss. 'There's shelter there, and food and water. I'll bet they headed there.'

A solution clicked into place for the Doctor. He reached across and tapped the Send button on Prentiss's wrist-phone.

'Get Roj on that for me, will you?' he asked, to a dark frown from Prentiss. 'I just realised I never finished telling him what he needed to do about chilling the plants.' The driver shrugged, tapped a code into the compact communicator and passed the whole thing over to his passenger.

'Roj? This is the Doctor here, and I didn't finish telling you about my nearly-fire extinguisher. Your air-conditioning plant. Yes. Set to maximum power, and temperature lowered to minimum. How? With that flexible plastic tubing from the pallets. Double-thickness will insulate it. It won't stop the plants, but it will slow them significantly, or repel them altogether. Yes it will. Because they're energy-tropic!'

The reply from Roj was fuzzed by static.

'Did you get that?' asked the Doctor, turning his head to better listen to the tiny speaker.

More hissing.

'The signal fades over distance,' said Prentiss. 'We don't have satellites up to give over-the-horizon coverage.'

'Yesssssss,' agreed his passenger, musing quietly and coming to a sudden, goose-pimpling moment.

The Doctor turned to look directly at Prentiss.

Except that what sat next to him wasn't Prentiss Deerfield, even if it managed to be a convincing simulacrum. It was the Rutan infiltrator.

Roj scowled at his wrist-phone. Fnorp the Doctor and his silly ideas! Using the bunker's air-conditioning plant to fend off the hostile –

He looked up to see Arpad and Montag standing before him and cradling a collection of miscellaneous electrical junk arranged in a straight line, part of which seemed to be a – portable disk-player?

'Yes? What is it now! I've just had that idiot Smith on, saying use the air-con to beat off those – those – plant things. All I need is another idiot idea.'

' "Floranimae!" ' exclaimed Arpad, to the mutual puzzlement of both Roj and Montag. He looked between them.

'A compilation term to describe our soon-to-be attackers. "Flora" being the latin for plant, and "anima" being latin for movement, and sounding close to "animal". Floranimae.'

Roj ground his teeth together silently for a second, to keep his temper under control.

'Yes. Very. Good. Thank. You. What did you come to see me for!' he blurted. Surely – in the name of the Immaculate – they hadn't come to tell him about a name?

Montag looked sideways at Arpad.

'Ah – well. We got to messing about with my personal disk player. You know, I brought it under the Personal Cargo allowance, with a collection of disks.' Seeing Roj's expression begin to darken, he hurried on. 'The thing is, I've always noticed that it has a really fierce ejection action. So Arpad here – well, anyway, he wired the ejection motor up to the mains supply. Let me demonstrate.'

Montag struggled to juggle the clumsy device around until it pointed to the bunker wall way above Roj's head, a long, flat plastic arm projecting an arms-length outwards from the disk player. Arpad took the long lead and plugged it into the power sockets under the desk.

'Ready,' he warned. Montag closed his eyes and pressed a button on the disk player's fascia. A silver streak flashed down the clear plastic guide, followed by a high-pitched smacking sound, a diminishing whine and an angry shout from elsewhere in the bunker.

Rubbing his head, Roj turned to look at a bright grey scar on the bunker wall.

'What the mooj was that!' he asked, simultaneously appalled and impressed.

'A CCD disk,' explained Arpad, proudly. 'So we have thousands of potential rounds and the ability to make more. Oh – I sharpened the edges on one of the grinding wheels.'

'Well keep your eyes open when you next use that!' warned Roj. 'Your high-velocity circular razor nearly parted what little hair I have left.'

'I want to try and remove the back plate, so we can load disks in one after the other, but that means - ' started Arpad.

'Never mind telling me! Go and do it. Go and do it quickly, those plant – those Floranimae are getting closer all the time.'

Rose stared haughtily at Kellerman, who shrugged blandly. He'd killed often enough before, killing again wouldn't bother him. A little female company out in the wilderness until his lift back home arrived would have been nice, but you couldn't have everything.

'The impact will knock you clear, and we're moving, so you'll fall – AHHH! JE- ' he shrieked, as a huge grey blur jumped for his hand and tore at it with an audible ripping sound. Blood splashed across the inside of the cockpit as the induction pistol fell to the floor, along with two of Kellerman's fingers.

Open-mouthed, Rose saw TEST rat 3 pause, spit blood onto the floor, then dive at her full tilt. The impact knocked her backwards, out of the open cockpit and onto the hard, unforgiving hull of Sun Gun, from where she pitched backwards again. Only long-forgotten reflexes and training, together with a forgiving sandy beach saved her from a painful fall.

'Thank you gymnastics class!' she muttered, seeing the hovercraft carry on into the shallow surf of the ocean's edge and keep on going, spray dashing up around the cab.

She half-expected Sun Gun to turn around and come back for her, but the hovercraft kept on in a straight line.

'Thank you,' she said to the giant rat, which lay on the sand, panting shallowly. 'Thank you ever so much.'

Shivering, she realised that her death had been about half-a-second away. Until the rat had dived into the hovercraft cockpit – which made her frown in reflection for a second. It couldn't have kept up with them by running – it must have hidden somewhere within the hovercraft!

'Did you make it run badly?' she asked. 'All that noise and shaking!'

'Yes,' signalled the rat. 'Bit wires,' it added. Then: 'Lots of wires.'

Rose stared out at the gently rippling sea. Sun Gun was still making headway, if slowly and with plenty of spray, and still in a dead straight line.

TEST rat 3 gave a huge shudder, and blood leaked out from the corner of it's jaw. Rose realised, with a resounding impact to her conscience, that the rat had bitten off Kellerman's fingers and ingested his blood. Which meant that the lining of it's stomach was being destroyed as she watched. That efficient human-protection planning at work.

'Oh no!' she cried. 'You're dying, aren't you?'

The giant rodent made a nodding motion, panting instead of trying to communicate.

Forgetting that she had, only days before, dismissed giant intelligent rats as monsters only slightly less horrid than – well, anything – Rose stroked the dying creatures head.

'Not mind,' it signalled. 'Mate dead. Not care.'

A drop of something fell on it's fur from her vantage point and Rose was astonished to find that she was weeping.

'Did good?' asked TEST rat 3.

'You did splendid!' she smiled and cried simultaneously. 'You saved my life and got your own back on Kellerman.'

The rat nodded, wrung it's paws together and died quietly on the alien beach, eight hundred light years from home.

Fuelled by an anger that came from somewhere beyond herself, Rose stood up and shrieked at the rapidly diminishing hovercraft.

'You bastard, Kellerman! You're a good example of a bad example! If there's any bloody monsters on that island you're headed for I hope they eat you alive! Slowly! Very slowly! Wolfing you right up would be a mercy! I hope they – Oh.'

From beneath the waves an enormous grey maw, fringed with fangs bigger than she was tall, erupted. Directly ahead of Sun Gun, the aircraft-hanger sized creature dove forward, engulfing the hovercraft in the space of three seconds before vanishing beneath the sea again. No more than a scattering of spume remained and although Rose remained on the beach for half an hour there were no more indications of survivors.

Well, he had a couple of seconds to see what was coming! she gloated.

Thijs nodded to Kaatje, who fired up the dismounted engine. Instantly it began to vacuum up loose earth via the flexible intake hose, flushing it up the erected piping. This stood in a tetrahedral arrangement, the central axial pipe being supported by the three outriggers. It had taken a couple of hours to get the whole thing upright, inertia being what it was, until the central pipe stood fifty yards high. Thijs moved in a small circle, hoovering up loose dirt.

Fifty yards in the air, dust and dirt began to boil upwards from the end of the central pipe, before falling back into the compound below.

'Stop! Stop!' yelled Thijs, being deluged by dirt falling from above. Kaatje killed the engine.

'Damn it, it's not spreading outwards!' he snarled. They simply didn't have time to go back to the drawing board. Damn it, that plabby Doctor Smith would have solved the problem in ten seconds flat!

'Ahem,' came a polite English voice from behind him. Thijs turned to see Eric French, possessor of an anachronistic name and a passion for the Freethie Rose Tyler.

'What!' snarled Thijs, feeling tired, sweaty, dirty and hugely unappreciated.

'Here's one I made earlier,' said Eric, parroting a joke he'd never understood. He showed a miniature mock-up of the piping array that Thijs and his wife had made: using plastic straws, he'd mimicked the tetrahedral array. Now, he took the central axial straw and applied force to the end that stood at least a foot clear of the rest. It bent, easily, and formed an angle of forty-five degrees to the main structure.

Thijs blinked at this simple transformation.

'Oh boy. Oh boy. Ohboyohboyohboy. Kaatje! We need another length of – no, wait, we need a spot-heating welder, and a ladder.'

Amir ibn Hussain spotted their behaviour and jogged over, threshing his arms around in a peculiar fashion.

'Whatever you're doing, do it quickly. Ghada and I have been watching the greenery on your periscopes. We're going to get attacked in half an hour or less.'

'Alone with you at last,' said Prentiss. Or, what pretended to be Prentiss.

The Doctor returned the look with one of his own.

'When did you realise?' asked the Prentiss-copy, still paying attention to driving.

'Just now,' drawled the Doctor, drawing out the revelation in order to calculate alternate scenarios.

'Oh, do tell. I long to hear logic from a contemporary. These humans are quite the benighted.'

'No single thing. However, you didn't react to the static charge that cleared the windows.'

'Trifling and inconsequential. Next?'

'Activating the wrist-phone on your arm. It didn't feel right. Insufficient density, I propose.'

The Prentiss-thing nodded.

'And the wrist-phone signal. It wouldn't fade out this close to Serendipity unless there were an alternate interference close at hand.'

Prentiss-thing shrugged.

'There is an element, a fraction, of energy leakage that we can't prevent. No human would ever notice or understand. You, Time Lord, are another case altogether.'

The Doctor stared hard at the driver.

'What next? Kill me, claim that the plants did it? Get back to your scoutship? Imitate me and further disrupt the mission?'

Pulling back on the throttle, the Prentiss-thing looked momentarily at the Doctor.

'Actually, Doctor, I haven't killed anyone so far.' Seeing a predictable reaction, the alien mimic continued. 'Oh, I would eventually have killed Prentiss and substituted myself. And, given sufficient energy input, I would have duplicated myself and eliminated his wife. But I didn't kill Prentiss.'

The bulldozer hit a particularly heavy clump of bushes, causing it to rock backwards.

'Who did, then?' asked the Doctor, feeling as if he were in a country-house murder mystery.

'Davinia. It wasn't until I saw her respond to Kellerman's mental control order that I realised why she did it. She was standing sentry outside the Baby Bunker when Prentiss came up, walking there to service the telescope mounting on top. She shot him on the spot, then dragged the body off and came back without it an hour later.'

Another victim of Kendal Kellerman, ruminated the Doctor, feeling his fists clench. When they caught up with him –

'Of course, Kellerman never realised what had occurred. Why should he? He left his obedient, mindless sentry outside whilst he got up to mischief inside. When he came back out, she was still his mindless, obedient sentry.'

Mindless and obedient and unable to recall what happened when brought out of her trance. Better she never discovered what happened, or a complete mental breakdown was a certainty.

'And you did imitate Roj, trying to spur Mike on.'

"Prentiss" sighed, then grinned.

'See how good I am at mimicking human expressions? Yes, that was a blunder on my part. I tried to speed things along.' The Rutan swerved to avoid more crawling, tendril-infested Big Bugs, leaving his passenger looking coolly back.

'What?' said the Rutan. 'I want to get off this miserable scorched rock just as much as the rest of you. Speeding things up would have helped do that.'

'Still not decided whether to kill me or not?'

'I'm not going to kill you, Doctor. You're far too ingenious about helping to keep everyone alive.'

I'll just have to accept that as the best I'm going to get, mused the Time Lord. Mind you, keeping everyone alive does include helping to keep our impostor here alive as well.

'Why are you here?' he asked, instead.

'Why? Because the Analytical Echelons of the Hive knew that those Beakies were poking around here in some desperate project. Of course, as you worked out, their homeworld got over-run by the Sontarans while they were away.'

Really and truly extinct. A derelict spaceship, a cemetery and an abandoned bunker. Not much to show for a million years of evolution.

'All those Lowry transmissions gave the game away. You humans – no, that should be the humans – were treading in the footsteps of the Beakies, which made the Analytical's interested again after such a long pause. So I get sent to investigate.'

Yet more treachery on Kellerman's part! realised the Doctor. Those so-called "orientation sessions" were nothing more than excuses to transmit information back to Earth in secret. Damn that technician! He'd been responsible for bringing this alien attention down upon the expedition, another complicating factor neither wanted nor needed. What had possessed him, to send out unauthorised messages – and what could they have been?

'I do know one thing you haven't worked out,' added the alien, deftly handling the dozer as parts of the exposed engine began to glow cherry-red with heat. 'The Beakies - ' catching sight of the Doctor's distate ' – okay, the Trinarians. Their sheer size and stature meant that those who were infected with parasitical plants did not become a mere means of mobility. Their cranium - '

'Of course!' cried the Doctor, slapping his forehead. 'Their skulls were too thick and too dense for any invasive assimilation! They became symbionts!'

Hostile ones, he recalled. All those bodies destroyed in the Defensive Dyke. A split between the members who stayed "pure" and those who "adapted" to ensure survival on a hostile alien world once their own had been invaded.

The current crop, to use a terrible pun, had other intents. There was –

'There it is,' calmly announced the Rutan. 'Baby Bunker. And a whole lot of plants around it. By the way, don't inform on me. Or I'll kill the humans you tell.'

Once again the Doctor gave a disgusted look at this casually-laid threat. The Rutan impostor ignored what it actually found to be a penetrating and unpleasant scrutiny, a scrutiny uncannily similar to those of the Debriefing Committee, to be undergone when it reported back to the Hive.

'Slow down and let's see what's there in the first place,' ordered the Doctor. 'I don't see any high-speed tractors.'

A volley of rattling darts ricocheted from the front of the cab, startling both occupants. Coming to a stop, the Rutan pointed at a Kakti bush at least fifty yards distant, which let fly with another volley.

Thanks to being at rest, the Doctor could make out the obscured bulk of a Rapid Rider, hedged about on all sides by greenery and parked up so that one side rested against the bunker wall and entrance. Most of the herbage was constituted of giant orthropods parasitised by Kink Bush seed pods, piled up in a great twitching mass.

'Must be blocking it in. Can you drive up to the rear and crush anything that gets in your way? Then do the same for the front?'

'Watch this,' said the Rutan with gusto, revving up and sending the dozer racing into the pile of hybrid besiegers. The result was a hideous collection of sounds as the victims were crushed and battered apart, leaving a mangled pile of oozing remnants with impressed track marks upon it. The Rutan had judged the distance so exactly that the Rapid Rider's rear bumper remained intact. Next, the alien reversed the dozer and ran it alongside the tractor, close enough for caterpillar tracks to snag and squeal against one another, close enough to crush more of the native wildlife into a pulp six inches high once they had passed by. Then, in reverse, the Rutan backed up and squashed the creatures up against the front of the Rapid Rider. Not as many this time, since a portion of them scuttled or stalked or flopped away before being crushed flat.

'Job well done,' gloated the alien, reversing to park the dozer alongside the tractor's cab.

The Doctor could see that the Rapid Rider had been parked hard against the bunker in an attempt to keep the interior safe. There was no sign of life in either the tractor or the bunker, no movement or lights.

Risking instant death, the watchful Time Lord crawled over his driver, then dragged the dozer door open, reached out and triggered the tractor cab door with his sonic screwdriver. One short and painful leap later, where he caught his ankle on the edge of the door, he prepared to start the engine, only for the Rutan to slide semi-bonelessly into the passenger seat alongside before slamming the cab door shut.

'Keep out unwelcome visitors,' it said. 'Hey!' for the Doctor had slid down the window that faced into the bunker.

'Hello?' he called, to no human response. Instead a mass of trembling, twitching greenery in the bunker stirred into wakeful life. While the dark interior of the bunker kept them relatively inactive, a direct stimulus like sound served to motivate them.

Then, too, unseen and un-noticed by either the Rutan or the Doctor, a pile of tarpaulin in the rear cargo section of the Rapid Rider began to twitch and tremble, too.

SEVENTEEN

Last time I volunteer for anything! swore Rogan to himself. He and Dan were sprinkling handfuls of what looked like gravel onto the soil out beyond the Dyke, directly ahead of the approaching mass of what Arpad had dubbed Floranimae. They were wearing heavy-duty gloves to prevent being poisoned themselves, which meant having sweaty palms. Rogan was convinced fear would have given him sweaty palms anyway.

He threw another couple of handfuls, scooped more out of the big plastic box that Dan held, and looked up to see the damned green wall still approaching.

'I reckon they're within thirty feet. Dan, what do you think?'

Dan glanced down at the tub. Still a good few kilos – pounds – left. Coming to a rapid decision, he threw the rest of the poison granules in a wide scattering arc before their foe.

'All done. Come, back inside.'

They scooted back up the Dyke, with Rogan having a moment of sheer terror when he nearly overbalanced and fell backwards. Once at the top they had to duck low to avoid being snared by Kink Bush tentacles that threshed around indiscriminately from their secure positions on the nylon netting.

'Come, lift this for me,' asked Dan, indicating the bottom of the netting, glancing backwards. With difficulty, thanks to sweaty gloves, Rogan managed to slide his fingers under the bottom of the taut nylon wall and lift it upwards. Dan got down on his stomach and crawled under. He stood up, safe on the other side, and substituted his hands for Rogan's, keeping the net up. Being able to look outwards, he saw what Rogan couldn't.

'Mon ami, vite!' he quavered. 'Quick!'

Still moving like a snake on his belly, Rogan bounded forward thanks to the propelling power of fear, his own and that in the voice of his colleague. He was very nearly completely under the netting when a slimy green tentacle lashed forward and caught his ankle.

Dan let the tight netting drop, but the aggressive tentacle didn't let go. He then stroked his gloved hand over it – the effect was electric and instantaneous as the tentacle flew free and retracted back under the plastic wall.

'You couldn't see,' said Dan faintly. 'When the fence was lifted, they came forward, very fast.'

Rogan rubbed his ankle.

'Thank the non-existent Lord for the poison on your gloves, eh?'

Further over to the east inside the compound, Ghada ibn Hassan witnessed the whole event via a periscope: a number of Floranimae raced out from the general mass when they witnessed Rogan pull up the perimeter netting. Most of them encountered the poison pellets strewn about minutes before, and abruptly danced backwards as if burnt. One parasitised Faterpillar found a gap in the poison layout and got all the way up to the narrowing gap beneath the netting. When Dan hit it, the reaction sent the creature recoiling down the steep outer face of the Dyke, where it literally danced around in a series of fits and jerks before lying still and stiff.

He killed it! realised the woman. Killed it with a single blow. That Big Bug poison was incredibly potent stuff.

'Hello?' quavered a faint voice from the cargo section of the tractor, and a wan face emerged from beneath a tarpaulin. Hastily, the Doctor pulled the window shut.

'Vicki!' recognised the Rutan, instantly adopting the Prentiss persona, having to clutch hold of the cab seat as the Doctor started the engine, engaged low gear and reversed back away from the bunker. He threw the tractor into a backwards half-turn, dialled up through successive gears and raced forward again.

'What happened back there?' he asked, in a tone so sincere that the Rutan felt envious.

Slowly, with pauses for sobs, Vicki explained. Beatrice had been killed by a collection of poison thorns, fired from a Cackti plant before they understood how dangerous they were. There were subterranean creatures living in the soil here, big things, big enough to break down the walls of the bunker. That was how Friday had been killed.

Then the aggressive plants outside had begun to find ways of squeezing underneath the tractor, forcing the four survivors to beat them off with whatever tools they could find, until a Sillipede got inside and attacked Arthur, badly injuring him before she'd killed it with a spade. Covered with Arthur's blood, Juni ran to the rear of the bunker, where a briefly seen creature darted from the collapsed area, catching her around the waist and dragging her screaming into the soil. Swoozie hid herself in a corner under a pile of abandoned tools and refused to emerge. Arthur had forced Vicki into the tractor, intending to drive away. Unfortunately one of the plant-creature hybrids had tentacles long enough to catch him from the other side of the tractor, and she witnessed her injured husband being dragged away.

There were too many creatures piled up around the tractor for her to drive it away, and then they'd managed to squeeze underneath and get into the bunker and Swoozie had screamed, but only once –

'Why did you do it?' asked the Doctor. There was no condemnation in his tone, only pity.

'We thought we'd be safe,' whimpered Vicki. Then she caught the view out of her window. 'Where are we going?'

'To find my companion. She's been kidnapped by Kellerman and I'm going to get her back.'

Despite her pitiful condition, Vicki heard the underlying tone in the man's voice and almost felt sorry for that horrid little plabby Kendal.

'How will you find them?' she asked.

'They're in Sun Gun One,' said Prentiss. 'Ground-effect vehicle. Leaves a nice big trail.'

He left out the part about having a nice big head start. Nor that the hovercraft could cross water and the tractor couldn't.

The Doctor was aware of both these facts. The first he couldn't do anything about; the second was a problem, but Kellerman would be a fool to try to cross open water in a vehicle not designed for that Not to mention that the expedition had absolutely no idea what kind of marine life swam in the oceans of ZLM Prime, or if it would have undergone the kind of dramatic alteration so much other life had in the aftermath of the stellar flare-up. In fact, piloting a vehicle that made so much noise on water – the energy delivered would have local life-forms flocking to see what made it.

It took half an hour before they came across the trails left by Sun Gun One, a track with deeper gouges than ought to be the case. That made them easier to follow but more of a concern for the trackers – did it indicate a fault in the hovercraft?

Not much further along, dots of darker soil in the track indicated a loss of fluid from the fleeing vehicle. They lost sight of these for a while, when crossing patches of grasses, but regained sight of them.

'It's in trouble,' said Prentiss. 'Running with a lesser air-cushion than it ought, and leaking. That's not good.'

'Nooo,' muttered the Doctor by way of reply, angling his head one way and another to catch sight of the leaks. He looked around, seeing plenty of agitated trees, infested giant insects and madly-dashing Sillipedes. If Sun Gun One conked out here, both occupants would be in big trouble. And it looked as if Kellerman was indeed making for the coastline – silver waves reflected sunlight in the near distance between the trunks of Razor Trees, making him think incongruously of Blackpool.

Next sign of trouble came in the form of small, thin pieces of plastic wiring that were scattered all along the path they followed.

Bizarre! reflected the Time Lord. What kind of mechanical problem causes wiring to strip out in small quantities over time? It would have made sense to stop and examine the debris, however he couldn't afford the time it would take.

After a short distance the gouges being made by the hovercraft became deeper, whilst the stripped plastic wiring was joined by bit of metallic circuitry board.

The internal mechanics of Sun Gun were being shredded! realised the Doctor. Unless Kendal had left Rose alone with a set of tools, which was doubtful in the extreme, this could only mean sabotage. Kendall mustn't be aware of how the vehicle was being eaten away –

'He's not heading for the ocean, is he?' asked Vicki, uneasily. 'We don't know what might be swimming around in there.'

'My thoughts exactly!' replied the Doctor. 'Of course he isn't.'

They smashed into a hedge of low-growing scrubs and onto a pebbled foreshore, the hovercraft's tracks leading in massively obviousness across the smooth stones, over the sands and to rushing surf at the water's edge.

'Whoops,' announced the Doctor, pulling the tractor to a halt, staring out to the horizon and feeling his stomach lurch. The nearest land was hazy blue on the horizon; thanks to the rapidly degrading performance of Sun Gun One he calculated that they were no more than an hour or two behind it.

There was no indication of any hovercraft, anywhere.

'Right. I'm getting out to have a look,' he announced in a tone that didn't invite debate or discussion. Feeling Vicki shift uncomfortably, he leaned back. 'Solid stone or sand underfoot. No place for plants to grow and their mobile and murderous cousins can't get close without making a noise.'

Outside, a cool, refreshing breeze swept inland from the sea, carrying a scent of brine and ozone. To left and right, for miles, the empty sands swept away in pristine arcs and dunes. A landscape unspoilt by any outside intrusion – except for –

'What's that?' asked Prentiss, leaning out of the cab window and pointing at a low mound of stones further along the sands.

Leaning and standing on his tiptoes, the Doctor frowned. The mound was at the demarcator between sand and stones, piled up into an ellipse with a much larger flat stone thrust edge-first into the ground at the tip of the pile. A strange, asymmetrical pattern had been scratched onto the flat stone.

'A rune? Ogham? Georgian? Sanskrit? No, Arabic. An arabic numeral - "3"!' he realised. Looking to left and right showed no other mounds that might be "1" or "2". Nevertheless, human hands had constructed this mound. If the hovercraft with Kendall wasn't here then the person responsible had to be –

'Rose!' he called, loudly enough to make both Vicki and Prentiss turn. 'Rose! It's the Doctor! Show yourself!'

Nothing. He shouted again.

Slowly, a long mound of dried sand not twenty feet away began to twitch and heave. A pair of slim hands shook themselves free from the sand, then a head with dirty blonde hair began to appear, shaking furiously. Rose gradually straightened herself up, sand cascading off her slight frame. Somewhat out of place, a biro was clutched in her mouth.

'For breathing while being covered in sand, eh? Smart girl!' grinned the Doctor, feeling immensely lighter in spirit.

Rose spat errant grains out and shook her feet gingerly whilst her mentor hugged her and led them back to the Rapid Rider.

'I got your message. "3".'

'It wasn't a message.'

'It was to me. What was it, then?'

'A grave. For one of the rats. It chewed it's way through the engine and bit Kellerman's fingers off when he tried to shoot me.'

A silent nod from the Doctor. How Rose's attitude was altered from that of a few days ago! Tact prevented him from mentioning it. She'd come to realise it in days to come, anyway.

She pointed out across the water.

'When the hovercraft got half a mile out, a great big fish came out of the water and swallowed it whole. One gulp – gone.'

'So the rat saved you twice over.'

Still feeling a lump in her throat, she merely nodded.

'One other thing you ought to know before we get back to the tractor. Prentiss isn't Prentiss, or human. Don't let on that you know!'

She agreed with a silent nod.

The Rutan impostor greeted Rose with a cheery wave and hello when she climbed back into the cab. Vicki sniffled a little, so Prentiss explained her story.

For Rose, it wasn't hard to keep Prentiss' status as a murderous alien spy out of her awareness, since she tried to comfort the weepy Vicki.

'I stayed on the sands. No plants there, you see,' she murmured to the grieving woman. 'Then I realised I was out in the open. No cover. Anything out there might spot me. So I dug myself into the sand.'

Vicki paused, her imagination caught.

'You didn't try to get back to Serendipity?'

'Nah! All that way on my own, with all those horrid creepy plants and insects out there? I wouldn't have lasted five seconds, let alone five minutes.'

A few seconds silence fell whilst Vicki pondered on this.

'So why did you stay there, in the sands?'

Rose shrugged.

' 'Cos I knew the Doctor would come.'

'But - ' began Vicki.

'I knew he would come,' said Rose firmly, finishing the conversation.

The Doctor concentrated more fully on other problems to hand. Those plants and animals attacking the Baby Bunker showed disturbing signs of intelligence and hostility combined. He suspected – suspicion wasn't proof, he chided himself – that either one of the creatures, hybrids, call them what you will, that had killed and assimilated Mike and his wife were behind the ferocious, antagonistic drive of that mass of plants.

This led to more disturbing conclusions. Why did these hybrid creatures go on the attack? The human staff at Serendipity had nothing that such an organism might want or need.

Then they're going to an awful lot of trouble to execute a pointless attack, he began, debating himself.

Organising a whole siege ring of parasitised wildlife implies a purpose with a rational aim. Those things had no reason to come and encircle Serendipity in the first place.

Agreed. What resources or artefacts did the expedition have that the parasite hordes might want?

Welllllll, nothing. Semi-intelligent mobile plants had little in common with humans or what they wanted or needed, bar sunlight and water, both of which were available at no -.

humans! Ah. There was the rub. Humans not Trinarians.

Humans! The resource that these mobile plants might conceivably want. Mobility, intelligence and stature in a single package.

'Do you have one of those phone thingies?' asked Rose of the Prentiss-imitation.

'Here,' it said, handing the wristwatch-sized over device to her.

'Hello?' she began, keeping the Transmit button pressed down. 'Hello, can you hear me? Can you?'

'Let the button go,' whispered Prentiss. 'Let – ah.'

'Hello? Hello, can you hear me? This is Rose. Rose. Rose who? Rose the Freethie! Who's that? Arkan. Okay, Arkan. I want you to get the TESTers all together. Yes, it is important! Yes – I do care if you're being attacked by monster plants! Yes I'll wait.'

She turned a blank face to everyone else in the tractor. Seconds later her wrist-phone beeped in a tinny fashion, until she answered.

'Rose here. Ah, you paid attention. This is quite simple. Get all the TEST rats together and direct them at one target at a time.'

From the tone of their reply, the person at the other end had a quibble.

'Don't waste time!' shouted Rose. 'Those rats are going to help save you!' A moment of inspiration struck her. 'Tell them that Rose asked you.'

When silence fell once again in the tractor she sat in a huff and watched the landscape pass.

'Get ready! They're nearly at the poison!' warned Ghadi, repeating the warning into her wrist-phone. She turned the make-shift periscope around, noting that the driven mass of Floranimae were uniformly up to the poison belt of granules scattered around the Dyke. In fact there was a thirty-yard gap where they were clambering up the Dyke on the eastern side, where Rogan and Dan hadn't been able to spread the poison before their enemy got too close.

Elsewhere the horrid things danced away from the poison, until the mass of creatures behind forced them forward. Within seconds a barricade of dead and dying hybrids began to form, until they eventually swamped and covered the poison and those following swept over it unharmed.

'Get the air-con over to the eastern side!' she warned. Her husband had managed that already, leading the cumbersome and leaking pipe over to the danger point.

'Go!' shouted Thijs, pressing the starter button on the dismounted engine unit. Fifty yards overhead the newly-attached diagonal piping began to turn as two people pressed round on a handle welded to the main scaffolding's axial pipe. Kaatje shoved the inlet on her roving pipe into the ground, the engine tone changed slightly, and gouts of dirt and dust began to vomit skywards from the top of the pipe, venting out far beyond the Dyke.

Ghadi turned to face Roj, who looked pale and tense, as well he might: trying to fend off an implacable foe with improvised equipment and not enough people.

'Eleven hours of daylight left,' she commented, wondering if any of them would live beyond the next sixty minutes. Catching sight of Montag and Arpad struggling with a bizarre contraption seemingly built around –

'Is that a personal disk player?' she asked, incredulously. 'What are you going to do, sing them to sleep!'

Scornfully and silently, Arpad fired a CCD disk over the protective nylon wall. Ghadi watched it hiss into the air and out of sight.

'It'll only work for so long until it burns out,' said Arpad, off-handedly.

'Keep your eyes on that mob outside,' ordered Roj. 'In fact, give me that periscope.'

By now the Floranimae were up to the netting, where they engaged in aggressive combat with the Kink Bush seed pods solidly fixed there. Thanks to the angle he was viewing from, Roj couldn't see how things were going, until almost a minute had passed and there hadn't been any breakthrough. One minute stretched into five, then ten.

With a sudden shriek, the nylon netting on the eastern side gave way, splitting from top to bottom and allowing a dozen parasitised Faterpillars to burst in, directly in front of the handful of staff wielding the air-conditioning pipe. Hassan shouted into his wrist-phone the instant he heard the nylon give way.

Roj dropped the periscope, unslung his police carbine and jogged over in a cold sweat. He could see the roiling mass of creatures slow and stagger as air at only a few degrees Centigrade hit them. They didn't drop dead, not quite, but they moved as if stunned into partial immobility. He blew one into a foul green haze with a shot from the carbine before Arpad and Montag arrived with their improvised flechette weapon.

The first disk went soaring into the sky, the second left a scar on the Dyke, then the rest began to slice the Floranimae apart. Sitting targets, they made only feeble efforts to escape, trapped by their metabolisms. More creatures, further back and about to enter the gap, were also slowed and nearly stopped, so Roj shot one of those, too. It went up in a geyser of browny-green slime before it's companions to either side were diced by the flying CCD's.

'Get some batons up here!' called Roj into his wrist-phone. Every spare member of staff had been issued with more of the ubiquitous scaffolding, cut into six foot lengths to be used as close-quarter weapons if things got truly desperate. When a dozen scared-looking staff arrived at a run, Christy amongst them, he tried to project a leaderly air.

'The air-con has stopped those things. I want you lot to smash them flat whilst they can't move! Go on, I'll cover you!'

Nobody was injured in the ensuing massacre as the scaffolding poles were used to kill every Floranimae up to the breach and slightly beyond. Twice more the tide of hostile hybrids surged forward, only to be immobilised and brutally smashed apart by humans made ferocious by fear. By that time the breach was blocked by the bodies of the fallen creatures and they fell back.

'Christy – we need new netting to cover this gap,' Roj warned her. 'And fast.'

His wife goggled at him for a second, wondering why he had addressed her in particular. Eric French came to the rescue, rolling his baton in the dirt to get rid of accumulated filth.

'If we get a bit of netting, oh, slightly more than twice the width of the gap, we could join the ends together, then stretch it between two bits of piping, like a belt. Stuck in the ground, we put it up - '

'Do it!' instructed Roj. 'Right away. Go on, scoot!'

Despite the desperate situation, Christy managed a parting quip.

'Crisis brings out the man in you, Roj!' she said, winking at him.

There was less welcome news from Lev, calling in by wrist-phone.

'The Big Bugs have all died. We've harvested a little more poison, enough to make up a few gallons of dilute. Stress, I think.'

'Make it up and chuck it over the netting.'

Glancing at the watch function on his wrist-phone, Roj couldn't believe that nearly an hour had passed. He broadcast a general announcement.

'If the netting is split again, I want everyone with a baton on either side of the split. Kill what comes through, don't wait for the air-conditioner to arrive.'

Silently he promised to thank Smith for that apparently silly suggestion about the air-conditioning system. And for the nylon netting, which seemed too slippery for the monsters outside to climb.

'Ghadi, tell Lev where to throw the last poison. We want to make it count.'

Why hadn't the mass of hostile attackers simply broken into the compound by virtue of sheer weight? He couldn't explain that. Did Smith know more about nylon and Kink Bushes than he let on?

Exhausted by keeping the clumsy periscope aloft, Ghadi rested it vertically on the ground, waving to Roj. He came over, turning in a full circle to keep an eye on all parts of the perimeter.

'There's a big, horrible thing that keeps moving round the back of all the other creatures, and it looks as if it's trying to drive them forward.'

Roj had a look in the periscope himself, seeing only the ring of attackers, which had thinned out perceptibly, to his surprise.

'You could get a shot at it from the top of the Bunker.'

Taken aback for a second, much as his wife had been earlier, Roj stared at Ghadi. What was he, some special force police commando? On the other hand, being atop the Bunker would give him a height advantage. Enough to see the ring of attackers around them.

Trying to move back to the Bunker with Ghadi's spare periscope, Roj discovered that he wasn't a sprightly teenager any longer. His back hurt and there were shooting pains all down the rear of his legs, and the police carbine seemed to have become incredibly dense and heavy. Panting heavily, he clambered clumsily up the bunker side, clawing at loose clumps of weeds until he staggered to the shallow earthern hollow atop the alien artefact, with the long-poled periscope.

From this vista, he could see the whole horrid ring of green, twitching, hostile attackers laid out around the base like a feral headband.

Ah! There! A giant, thrashing hideous parody of a human being, all green tentacles where limbs or a head ought to be.

The figure stood half a mile away, and Roj only slowly realised that the supposed "bush" the creature was talking to was actually another, similar, giant threshing monster. He focussed the sight at nine hundred yards, adjusted for wind and fired.

EIGHTEEN

Vicki, exhausted and still coming to terms with the death of her husband and colleagues, lay on the tarpaulin in the cargo space and went to sleep, snoring occasionally. Rose threw sidelong glances at "Prentiss", whose demanour changed when the other woman fell asleep.

'You told her, didn't you?' the impostor asked of the Doctor, who merely nodded.

'I'm not having her kept in the dark. Besides, she's discreet.'

The imitation sneered, convincingly. Rose dropped her pretence of aloofness and stared hard at the Rutan.

'Why haven't you killed us? The Doctor says you Rutans are walking batteries.'

'He wants all that accumulated data about ZLM,' interrupted the Doctor. 'Or we would have been turned into a couple of human kebabs.'

Prentiss grinned in a teeth-baring gesture similar to but not quite a smile.

'Ugh! Don't do that!' shuddered Rose.

'You've done undercover work with humans before, haven't you?' asked the Doctor, conversationally.

'Of course, amongst the Pioneer Corps, for years. You don't acquire a library of responses like mine quickly.'

'Hmm. Yes,' drawled the Doctor. 'You appear to have picked up some rather dubious responses, if you don't mind me saying so.' The feral glee at crushing the hostile plants at the Baby Bunker came to mind immediately. 'You realise that the Hive will have you executed for displaying – what's the phrase? – "Symptoms of Cultural Contamination"?'

This seemed to disturb the impostor's facile manner.

'Nonsense! I'm too valuable to dispose of like that!'

Without replying, the Doctor slowly grinned. The Rutan flushed a dark green colour, which to Rose made him – or it – look on the brink of death. The lapse in disguise was even more telling for the Doctor: a Rutan that considered itself as anything but a component of the Hive was, ipso facto, a renegade. Deeming itself "valuable" put it even further beyond the pale, and the Rutan had recognised this as well – hence the verdant skin tones.

'I'm doomed,' it muttered, after a long and painful silence. 'Aren't I?'

The Doctor slowed the tractor, peering intently at passing hybrid creatures.

'Nooooo. Not entirely, anyway. Now, isn't that interesting - ' and he suddenly recalled where he was. 'Not doomed. There is a refugee culture in the Magellanic Cloud, you know.'

This was news to Rose, even if the Rutan seemed to know a little more than her. She opened her mouth to ask a question before the Doctor forestalled her with an explanation: refugees from Earth had set up home in the Lesser Magellanic Cloud, spreading out over a dozen worlds where religion, sexuality, political belief or language were tolerated instead of being capital offences. Nor was that all. Even more remarkably, Rutan and Sontaran deserters from their incessant war had settled there, in a reasonable facsimile of peace.

The Rutan imposter rubbed it's chin with a hand, copying a gesture of human concentration.

'Interesting. Didn't know the Sontarans were present. We've known about the human presence there for quite a while, but they aren't a threat. Imagine being driven that far away by the Grey Empire!'

The Doctor slowed the tractor again, peering out of the window and replying in that abstracted way he had when doing multiple tasks simultaneously.

'It won't last much longer. Yeah, falling apart as we speak.'

'Good,' said the imposter, with feeling. This surprised Rose; she imagined a faceless member of a "hive" would approve of a humanity stamped and shaped into as near-identical as possible. 'Less competition.'

'More fool you, then!' snapped the Doctor, attention back on the driving. 'After the Grey Empire collapses comes the Human Commonwealth, and when they get to the stars your little squabble is going to get snuffed out.'

The Rutan sat in a huff for several minutes after that: clearly it had been nettled by one of the biggest conflicts in the history of the Galaxy being referred to, dismissively, as a "little squabble".

'Surely getting narked at what the Doctor says isn't the sign of a good little Rutan?' commented Rose, snidely.

She got a warning glance and tilt of the head from her mentor; nothing said, just the implication that she ought not to be quite as cutting. For a long time after that they all sat in silence, only soft snores from Vicki breaking the monotonous journey.

Feeling rather silly, Arkan led his array of rat warriors out of Serendipity and into the grimy twilight of the embattled perimeter. He'd not been outside yet, being occupied with looking after the giant tubing running from the air-con plant and making sure it didn't suffer any failures.

The air was full of dust – and no wonder! The Piersons had assembled a giant pipe assembly that was hoovering up earth and spouting a giant plume of dust into the air beyond the Dyke, the pipe being turned by two sweaty staff pushing hard at a capstan. Nearby, Montag was applying a dressing to Arpad's hands; a smoking heap of shattered electronics and plastic at his feet implied he'd suffered scorching whilst handling that bizarre device he'd cooked up.

Arkan checked that the giant rodents were following. They were, stopping to bob up and down on their hind legs and take in the scene. Fifteen (of their original twenty) furry faces looked at him, signalling "?"

He pointed at the nylon fencing, which bulged inwards at several places. It had obviously been split at one point, but a hastily-arranged inner-fence section had sealed that breach.

'Attack anything that gets into the compound!'

The rats sent out four sentries to cardinal points, keeping themselves in a compact mass, and operating with impressive precision.

That's why we engineered them, Arkan realised. Willing and intelligent helpers. A slap on his back made him turn around to see Roj. The Pierson's motor made so much noise the mission leader had to lean in close to be heard.

'I got one of those things that seem to be leading them. The other one got away.' He had the carbine slung over his shoulder. 'No more charges left. What are the rats doing out all at once?'

Arkan explained, leaving Roj frowning. He didn't know if the giant rats would be any use, or just get underfoot. Looking at his watch, there were still nine hours of daylight left.

'Can we last out till nightfall?' asked Arkan, interpreting the look accurately.

'With a bit of luck,' replied the leader, gloomily. He noticed Arkan's blink of surprise. 'Then we have another eighteen hour day to get through. We've beaten them off today but there's an endless supply of Floranimae out there. A whole planet's worth.'

A high-pitched squeal of abused plastic went up from the nylon fencing to the east of the compound, a horizontal tear appearing in the black fabric three feet above ground level and splitting the fencing open in a gap ten feet across. Immediately, green tendrils began to seek and pry and drag the damaged material down.

The sentry rat gave a long squeaking call, just as Roj shouted for the weary, grimy, sap-spattered baton carriers to meet this new threat. The TEST rats arrived at the torn fencing first, darting and jumping, biting viciously until a slew of severed tendrils lay, twitching slowly, at the foot of the Dyke. Christy sprayed the gap with a fire-extinguisher, a couple of other staff battered odd tendrils still trying to get inside and that particular emergency was over.

Christy threw the extinguisher away; they now only had two left.

Roj looked at his wife without truly seeing her. No more poison, no more plasma carbine, only two extinguishers left. The fencing had been breached twice and there were still six hours of daylight left. They didn't even have a vehicle to try and escape in.

'Hello!' came a cheery voice over his wrist-phone. Roj looked at it in utter surprise at the man's jovial tone.

'Hello?' came the surly reply from the wrist-phone the Doctor had taken from Vicki whilst she slept.

'Roj! Just the man! We're on our way back with Rose and Vicki. Sorry, but nobody else survived. Should be there soon.'

'If I were you I'd stay away. We're still under attack here and even if we last out today - '

The sentence remained unfinished.

'Oh, don't be so grumpy!' chided the Doctor. 'Things aren't as bad as you think.' He gave Rose a wink.

She felt as surprised as Roj, and looked it.

'Not as bad!' snapped Roj, the anger coming over despite the distance and poor reception. 'Not as bad!'

'Reception's a bit rubbish, you've got an echo,' teased the Doctor, before abruptly becoming serious again. 'Roj, if you remember, Cholon was puzzled how the Kink Bush propagated. No seeds, no transmission vector, no other way to spread. Except now we know it spreads by parasitism. It's not a good parasite, far too intrusive and consumptive, it eats the host away entirely and the host falls apart!'

Silence from Roj, even though the circuit remained open.

'I've seen this happen out here myself already, a couple of times. That's how it spreads itself, through a host that is consumed into exhaustion. The Kink Bush begins to grow on that spot.'

'How does that help us?' asked Roj.

'The process has begun already, Roj. I've seen it happen. Only in a couple of cases so far but it will accelerate. You won't have to endure beyond today. But keep an eye open for those hybrid creatures derived from Cholon and his wife – they are the real danger.'

He didn't elaborate and signed off.

'What makes them so dodgy?' asked Rose, having overheard all. 'Being almost intelligent?'

'Yes. They are probably aware of the limited time they have to attack and assimilate other human beings before their Kink-infested minions fall apart.'

Rose wrinkled her nose at the thought of creatures with a hijacked mind and body. Compared to them, the giant rats were almost cute.

'I don't suppose you're at risk,' she almost accused the Rutan. It turned a gloomy, sunken face to her, pallid and ill-looking.

'Rose!' warned the Doctor, quietly. 'Don't bait.'

'Well, it could copy one of them. Or one of us. And make a getaway, or zap anyone who got in it's way.'

The Rutan, clad in a convincing array of Prentiss, shrugged.

'Which wouldn't get me very far, according to your smart friend here. Once back amongst the Hive, I get zapped myself. It's not a future to aim at, really, is it?'

The pallid complexion remained. Perhaps retaining a convincing human exterior mattered less than before to the Rutan. Rose didn't look on the shape-shifting alien organism with any more pity than before. Perhaps a little more understanding, but definitely no more compassion. Still, there were one or two questions unanswered.

'What was the Pioneer Corps that you were in? Part of the army?'

The Rutan made a tut-tutting noise.

'There is no "army" in forty-second century Earth. Planetary development. Wrestling a wholesome ecosphere from the noisome original. Decades in the process. Men amongst men. Harder than the hard. To be - '

Rose made a cutting-off gesture, having heard endless variations of the same from her male acquaintances off the estate. Mucho-a-macho, as her mum used to dismiss them, adding "big car small endowment" frequently.

The Doctor, of course, knew the background already. He understood the Pioneer Corps to be a vanguard who set up footholds ("planetheads") on potentially terraformable worlds, enduring vile conditions while the immense conversion plants got to work. High wastage rates, an ecological attrition that the Grey Empire could afford, to ensure it got more worlds to occupy. If this Rutan had been securely ensconced amongst a hundred thousand human Pioneers then it would have been there for years, at the least. Long enough to pick up bad habits, habits of the mind. Bad habits that became part of the adopted personality, which was adopted for so long that it became the original.

'What is that!' asked the Doctor, leaning so far forward that his nose nearly rubbed the windscreen from the inside.

Rose leaned forward too, looking across the horizon. A haze blotted out the distant landscape, and the middle was rather indistinct.

'Oh hola!' she swore. 'That's not a nuke, is it?'

Despite himself, the Doctor couldn't help smirking. Rose Tyler had a very narrow view of what a nuclear detonation might look like –

'It's not a nuclear weapon.'

Nonetheless, it was a gigantic column of upchurned earth, being shot high into the air over the bunker. Dust had spread out on all sides, clearly affecting visibility, and the sunlight was enfeebled and wan.

'Clever chaps,' murmured the Doctor. 'Cutting down the daylight.' He ran the static charge over the cab windows to repel dust and dirt.

'Aha!' crowed the Doctor, pointing triumphantly. Rose and the Rutan looked, seeing only a clump of Kink Bushes. 'This area was all blasted barren by the Trinarians, wasn't it? So that's proof of the attackers falling apart.'

Vicki abruptly snorted and sat up equally quickly, escaping from a bad dream that involved things coming at her from the shadows –

'Where are we? Where are we?' she asked, plaintively.

'Nearly back to Serendipity,' said Rose. Vicki buried her face in her hands and wept.

'Oh do be quiet, woman!' snapped the Rutan. She stared back at what was, to her, Prentiss.

'Rose – check and see what the green and gruesomes are up to,' said the Doctor, tossing his pocket telescope over to her.

Still laying siege to the compound, it seemed. There was a solid wall of slowly threshing greenery blocking her view of the black nylon netting. Smaller groups of roving, twitching tentacled monsters wandered aimlessly around the perimeter and even as Rose watched, an entity so infested with Kink Bush that she couldn't identify it fell apart, leaving a static mound of immobile green.

'They still seem to be trying to get into the compound. But not very hard.'

Throttling back slowly, the Doctor brought the tractor to a halt: his idea was to remain still and silent for as long as necessary, waiting until the accumulation of dust in the air and sunset reduced the attacker's mobility to practically nil. Why risk anything?

The Cholon-thing's thoughts ran sluggishly. It was aware of the shrouding dust, feeling it lying on sensitive tendrils. The energy it derived from the sun was lessening. The infested minions it had chivvied and harassed into attacking the source of more humans were starting to reach their last phase, falling apart and becoming mere plants again.

And now it was alone. A giant gout of energy from far away had disintegrated it's fellow converted creature, energy emitted from a weapon. The Cholon-thing had scuttled away to safety, away from the energy instead of toward it as the other hybrids had done.

Now, it felt awareness of another energy source, a small vibratory one over – it flayed tendrils around in an arc – there. The emissions gradually ran down, but not before the creature had marked the location.

Such an energy source meant humans. Not that the creature was able to rationalise so precisely or concisely. Rather, it's thoughts ran along two concepts: prey, and attack.

Silently, slowly and with certainty, it slid heavily into the soil, humping up a mound that covered most of it's body and began to edge towards the prey.

'Why can't we just drive in?' complained Vicki.

'Because we'd have to drive right through the protective netting to get in. The front entrance won't be accessible.'

Rose wondered how the Doctor knew that; later on, when she witnessed the Weepy Willow swollen to boabab-like proportions thanks to dining on endless hybrid attackers, she understood. A person might have squeezed past the bloated trunk, the Rapid Rider would not have. At a gesture, she passed the telescope back to the Doctor, who scanned the whole visibile perimeter very carefully – which meant he missed the greater danger nearby.

Vicki spotted the tendril first as it snaked silently up the cab window, to be joined by others until a solid mass appeared, pressing hard against the window. Stricken with fear, she could only point and gape, until Rose turned to see what the movement was.

'Doctor!' she yelled, causing the Time Lord to jerk away from the window in surprise at the giant mass outside.

'Don't worry, it can't get in,' he assured them, the Rutan shifting nervously alongside.

A nasty grating crack sounded as the window began to break. The laminate construction didn't allow it to break apart, instead it began to unseat.

'Out! Go!' shouted the Doctor, being beaten to a hasty debussing by Rose and the Rutan. He dragged Vicki over the back of the cab seats, making her howl in pain as her shin caught.

They dived out of the opposite cab door, Vicki losing a boot to the snatching tentacles of their pursuer.

Rose got a clearer look when the hybrid tumbled out of the cab, standing erect. Over two meters tall, all resemblance to a human had been lost, apart from the smaller bundle of tendrils that sat atop the giant creature. These twitched in their direction, swinging back and forth.

The Doctor mentally kicked himself. Of course, with the unsuccessful attack on Serendipity getting nowhere the human-hybrids would look to any source of fresh humans to assimilate – and here were four victims naked in the open. Where was the second converted creature?

Of course simply being out in the open was dangerous – there were still feral fauna on the loose. In fact he caught movement in the corner of his eye, a vague blur against the background of dust and airborne grit.

'Doctor! What do we do?' hissed Rose.

He raised a finger to his lips, slowly. Equally slowly, the Cholon-thing swivelled to face Rose, who froze into silent immobility.

This stalemate might have continued indefinitely or until nightfall, had two things not occurred: the movement that the Doctor had earlier noticed became a spiney silvery streak, a transformed Sillipede bristling with spines and headed directly at them. The tiny, beady-eyed head whipped round and pointed straight at the Doctor as the savege chitin torpedo winnowed towards him, delicate yet deadly.

The second event was a shriek of horror from Vicki, who clasped her face in her hands and stared at "Prentiss", whose skin had turned a bright, flourescent green.

Instantly, the giant mass of tendrils pointed at Vicki, until the Doctor threw out his hand and shattered the attacking Sillipede apart with a blast from his sonic screwdriver. Such an output of energy could only have one outcome and the hybrid bounded forward, lashing out with the longest tendrils it had, generating a fine spray of otiolising slime. The Doctor's athletic bounce backwards prevented the long green tentacles from grasping him, yet one still hit his chest with sufficient force to bowl him off his feet. Watching this theatre of horror, Rose scooped up a rock and hurled it at the green monster poised to spring, knocking a fist-sized hole in one tendril. That smaller bunch of green tendrils lashed round and the huge mound altered orientation, thrashing in all directions and scattering everyone headlong. Rose fell on her back, winded, dust-crusted slime dripping from her boilersuit; partly paralysed, barely able to breathe let alone even stand as a frothing shadow fell over her.

Whilst danger stalked beyond the Defensive Dyke (literally) those within were beginning to look around in wonderment at the lack of offensive action by the Floranimae outside. Having poured ton upon ton of grit, rock and earth into the air, the Pierson's suction motor was beginning to sound worn and weary, and there was little loose earth left to be sucked up within fifty yards of the engine.

Twice more the beseigers had split open the nylon netting and lurched inside, being shredded in furious counter-attacks by the TEST rats, who had suffered several dead in the process, and baton-wielding humans. To everyone bearing witness, the attackers moved more sluggishly than before, even when they weren't being blasted by icy-cold air from the air-conditioning system. Peering over the netting with periscopes revealed more and more stationary Kink Bushes, still feral and threshing around, but no longer mobile.

Roj and Christy met in passing, the mission leader hardly able to believe that their only injury so far was a pair of burnt hands.

'That plabby Smith was right!' asked Christy. 'They're falling apart.'

Before answering, Roj looked up at the sun, Zai Long Mian. The source of all their troubles. The wan disk swam in a dirty grey sky, dimmed into redness by the volume of dirt shot into the air. Under gravity, the dust and grit was slowly settling, but it seemed to have been enough to render their attackers sluggish and inept.

'Lack of sunlight to drive them,' he answered. 'Hey, Ghadi!' he shouted.

'What?' came the weary reply.

'Have you seen that big mass of tentacles lately? It seems to have vanished.'

With aching limbs, Ghadi lifted the periscope and looked in a full circle, twice, just to be sure.

'Nowhere to be seen. Perhaps it fell apart? They seem to be doing that a lot.'

An unwanted shiver ran down Roj's spine, a feeling that had nothing to do with the air-conditioning tubing nearby.

Fallen apart? Well, he could only hope so.

Before the massive hybrid could simultaneously crush and assimilate Rose, it suddenly felt the impact of needle-sharp spines hitting all down it's rear. Not a problem individually, but these slashing barbs simply didn't stop coming.

Rose backed away on her elbows, witnessing the truly remarkable sight of the Doctor throwing Sillipede spines in a manner similar to a card dealer. He effortlessly took spines from a bundle held in his left hand, flicking them with his right hand at the rate of five per second. Their impact into the alien monster was audible, a meaty whack-whack-whack that sounded like a joint of meat being hit with a mallet.

The monster might have overlooked one or two spines, but fifty or sixty high-speed hurled spines meant it's physical integrity was being challenged. It backed away from Rose and turned to face the Doctor, streams of ichor running down it's impaled body. With a gap of only ten yards between them, the creature managed to gain a fair amount of momentum as it charged the Time Lord, determined to destroy the source of the devastating barbs.

Sheer inertia meant that the laws of physics would prevail; the Doctor didn't have the space or time to evade the massive monster bearing down on him.

'Run!' he bellowed, locking both hands together and forward defensively.

A sizzling wave of energy rolled over him, giving him a bad suntan, boiling hidden moisture out of his camel-hair coat, frizzing his hair into an embarassing perm. The expected impact of the Cholon-monster never happened.

Opening an eye, warily, the Doctor witnessed a giant threshing mass of tentacles roiling madly and randomly over the earth several hundred yards away. Sporadic flashes of bright green light illuminated the monster from the inside, at which great green gouts of sap and tentacle would fly off into the air.

'What's happening!' quavered Vicki, still lying prostrate. 'What - '

'Prentiss was the Rutan,' said Rose, helping the stricken woman back to her feet. 'And he's taken on that big bundle of slimey snakes.'

Out on the scorched earth of ZLM Prime, the Rutan prevailed. The Doctor witnessed a gently glowing green sphere, trailing pseudopodia, erupt from the casserolled remnants of the Cholon-thing. Whilst the Rutan was mobile, and vivacious, the hybrid remained a pile of steaming green offal. It rolled towards the three survivors.

'Now,' it droned in a Rutan's peculiar electronic monotone, warbling madly. 'Now - to see to you.'

Which, the Doctor translated, meant: You Are About To Die.

NINETEEN

Under-Administrator of the Seventh Rank (Provisional) Zabulon Black stared at his big, black desk-mounted communicator with a feeling very nearly approaching distaste. Being a good Administration Servant, he didn't allow himself the luxury of such a negative emotion. It wasn't productive.

Shrugging, he began.

'Secretarial Assistant? I need to put in a Special Communication via Hyperspatial Coil.'

The communicator spoke back to him.

'Very good, sir. Where will the call be made to?'

'To the collection of Moral and Political offenders on – what's it called? I forget.'

'ZLM Prime, sir. I'll get the routing permission and protocols sorted. Thirty minutes or less.'

'Thank you,' said Black. It was polite to acknowledge efficient subordinates. He sighed, not really looking forward to confirming what that criminal Kellerman had negotiated already. Really, he must be so desperate to get back into Criminal Operations! And he must have been desperate to resort to extortion whilst employed there in the first place.

Still, reflected the administrator. Rules were rules. Procedure was procedure, The Administration existed because it was founded on both.

All the same, eight hundred and fifty light years distant, with a sun that might blow up at any moment –

The Rutan began to morph back into human form, not getting all the way there: it had a human shape but glowed a faint green, without any facial features. It attempted to walk forward, staggered and fell headlong.

Gingerly, the Doctor approached the alien. The faceless, featureless form rolled over and looked at him.

'Poisonous. What a surprise. Don't come near me.'

Vicki was pressed up against the inside of the Rapid Rider's cab, having locked it shut, much as her eyes.

Rose carefully kept a good metre between herself and the Rutan.

'I'm not going to kill you,' the alien warbled. 'There may still be poison on me. Don't touch.'

'We could try to rinse it off - ' began the Doctor, in a gentle tone that made Rose realise the alien was dying, not simply unwell or sick. He leaned in closer.

'Nah,' replied the Rutan, reverting to human slang. 'I'm past help. Mind you, I was before, according to you.'

The faint green glow faded even more.

'Those Lowry cores are under the shack,' added the Rutan. 'No good to me now.'

'Thanks for saving us,' added Rose.

A sound like a laugh came from the alien.

'Who'd have believed it - Rutan saves humans. I wasn't trying - ' and the voice trailed off into silence as the green glow died away, too.

The Doctor stood up, palming his hair back into a reasonable resemblance of a hairstyle.

'Did it kill that horrible monster to save us?' asked Rose. 'I mean, it doesn't seem likely.'

Rubbing his chin, the Doctor paused before replying.

'Perhaps. Perhaps it did, Rose, without realising. Spend long enough amongst humans and you start to think like them, and self-sacrifice is practically unique to your species.'

Before getting back into the tractor, he took time to wrap the dead alien in a tarpaulin and secure the corpse in the cargo section. Evidence, for one thing.

Vicki, not unexpectedly, kept her eyes shut at all this activity. She refused to move or speak and sat in traumatised silence, forcing the Doctor to whisper gently into her ear whilst rubbing her left temple. Gradually her drawn face relaxed and she slumped sideways, snoring in an undignified manner.

'Therapeutic hypnosis,' he murmured to Rose as he fired up the tractor's engine. 'It'll keep her relaxed and able to deal with things better when she wakes up.'

'Wow,' was all Rose could muster.

'Well, living up to my name!' he grinned.

They remained sitting in the cab for hours, until the shadows outside got longer and darker, ZLM sank to the horizon and the giant fountain of dirt from Serendipity had long halted. The Doctor dealt with the enormously swollen Weepy Willow standing guard by simply driving right over it in low gear, turning it into an enormous pulpy mass, unpleasant to look at and disgusting to smell.

Headlights on full, their return to the camp was witnessed by small groups of grubby survivors, looking startled and pleased at still being alive. Rose saw the nylon netting infested with a solid wall of Kink Bushes, barely moving now that the sun had gone, and masses of the green bushes dotted all over the outer wall of the Dyke. Lacking any intellect of their own, the attackers had lost interest in their attacks and wandered away once the driving force – the hybridised Cholon-thing – had gone.

Sounding a loud blast on the klaxon, the Doctor drew to a halt and collapsed the cab, tweaking Vicki's earlobe to awaken her. She yawned, blinked, stretched and slowly climbed back down to meet a semi-circle of mission members. The Doctor and Rose followed, looking at the none-too-friendly faces of those who hadn't run away.

'So where are the rest?' asked an accusatory voice.

'Dead,' explained the Doctor, calmly. 'Killed one by one. Quite traumatic enough without Vicki having to endure a barrage of questions.' He gestured to Rose, who led the sole survivor away towards the bunker, before he took stock of the compound.

'Any casualties?' he asked.

Roj, grubby and weary, approached.

'No – well, Montag burnt his hand when his gadget blew up. Oh – Rose would tell me off for saying "no". Half a dozen of the TEST rats were killed.'

The mission leader looked around the people assembled, before turning back to the Time Lord.

'All the insects infested with Kink Bush stopped trying to get in when they came into contact with the Kink Bush pods you got us to fasten to the netting. Did you know they'd do that?'

A shrug from the Doctor.

'Not for definite, but it was a fair chance. Chemical or a function of that crude nervous system they possess, prevents them turning on each other.'

'I can't believe we're still alive,' muttered Rogan, at Roj's elbow.

The Doctor pointed at the giant piping structure, then at the air-conditioning tube and at a TEST rat snacking on the remnants of a Big Bug.

'Human ingenuity, Rogan! That's what I like about your species! Necessity being the mother of invention. Plus, you weren't using energy weapons to defend yourselves, unlike the Trinarians.'

'Where's that fnorping plabby Kellerman?' asked another voice at the back, a refrain taken up by others.

'Dead!' replied Rose, having returned from the bunker in time to hear the question. 'Swallowed in the hovercraft by a big beasty out at sea.' A chorus of pleased comments came in repsonse.

'What happened to Prentiss?' asked Roj.

'Your Prentiss wasn't actually Prentiss. The Rutan had – taken his place,' said the Doctor, choosing not to mention the actual manner of how the real Prentiss had died. That unfortunate woman didn't need to know even more about what she'd done.

Of course there were shocked responses to this uncomfortable revelation, people remarking how they never noticed, or what they'd done with or said to the impostor. They were especially grateful for the revelation that the missing Hyperspatial Transmission Coil cores were hidden so close to hand, and indeed grateful to have them at all. Half a dozen staff went to dig for them. The Doctor filled in a few more details as he and Rose headed back to the bunker. A small row of six graves had been dug to one side of the structure, with a plastic panel serving as a substitute gravestone, making Rose do a double-take.

'Ah – the TEST rats,' explained Roj. 'Frankly, I don't think we'd have got off so lightly without them. They tore those Floranimae to bits.'

Rose darted a dark glance at her companion, who waved his arms in admission without having to look at her.

'Okay, I was slightly in error. More than intelligent spanners. Okay?'

She punched him lightly on the arm.

'Never thought I'd see the day you admit to being wrong!' but she grinned at him.

Inside, Rose took her place in the long queue for the showers, feeling a sense of relief at having come back intact from a kidnapping by – and then she recalled a snatch of conversation that Kellerman had gloated over. How had it gone, exactly?

Unwilling to give up her place in the queue, she caught sight of a TEST rat and whistled it over.

'Bring the Doctor over, will you?'

The rat gave a nod and vanished, reappearing with the Doctor minutes later.

Whilst Rose queued, the Doctor went to see how Vicki Dawson was coping, after a quick visit to Nils and Kristen.

Not too well. She was huddled on her camp bed with a hostile audience of five other staff, busy telling her what they thought of the ill-advised theft of supplies and Rapid Rider.

'That's quite enough,' he said, quietly but firmly. Christy Taylor, the mission leader's wife and apparent leader of the group, objected to his objection.

'She and those others put us all at risk! We needed people here to cope with those monsters outside, not to mention all the stuff they took, and one of our only two vehicles to escape in!'

'Do you know one of the reasons you have survived and the Trinarians didn't?' asked the Doctor, not being rhetorical.

'No. Do tell!' glowered Christy, ladling the sarcasm on.

'Unity.'

The single word, said without explanation, stopped Christy. She blinked, frowned and opened her mouth, then shut it again.

'Unity. The Trinarians turned against each other. I dare say one faction wanted to return home, even if it was over-run, and the other faction wanted to stay here, even if that meant becoming part-plants in the process.'

'So?' asked Christy, less sarcastic than before.

'You people here pulled together and endured successfully. Vicki's group split apart and suffered accordingly. There's a lesson - '

He stopped as a TEST rat tugged at his coat hem.

'Excuse me, I think I'm needed elsewhere. Unity. Remember that.'

The rat led him back to Rose, standing in line for the showers.

'Doctor, Kellerman said something when he had me at gunpoint. He didn't care what he said, I think, because I wasn't going to live to tell anyone.'

'Go on.'

'He said "I won't need you when the relief ship arrives, you or anyone else". Like – oh, I dunno. Like it was his own private spaceship.'

Her companion said nothing, merely wrinkling his lips.

'Oh, well, it was probably just him talking. Nasty plabby,' she said, dismissively.

The Doctor didn't feel quite so sure. He mused on this whilst walking and found that his feet were leading him to Roj's cubicle. The mission leader was leaning with his head on the desk top, asleep, until he heard footsteps.

'What?' he asked, blearily. 'Oh, Doctor Smith.' He rubbed his eyes and yawned hugely. 'Sorry, it's stuffy in here and will be until the air-con's been on for a while.'

'What are your arrangements for getting back to Earth?' asked the Doctor, dropping his lanky frame into a chair.

'Oh, that. We get a relief starship once our nine months are up. Or if we had an emergency, then The Administration would try to get one out to us soonest.'

'How long do you have to go?'

Roj calculated rapidly.

'Another three weeks or so. Not long. Oh, I see what you mean, Kellerman being our Lowry technician. No, all we have to do is activate the Emergency Transmit. Does it all for us.'

Under the scrutiny of the visitor opposite, Roj felt an increasing sense of unease. Why did this alien stranger come to ask that question in particular? He opened his mouth to ask the question, only to be forestalled.

'I rather wonder what Kellerman was actually up to on his own in that Lowry shack. After all, if he and Davinia were in there, he could get up to whatever he wanted.'

Roj tutted and shook his head.

'What could he do! The worst is that he sent our data to Earth.'

The Doctor straightened in his chair, shrugging his shoulders to make the camelhair coat fall properly.

'You've got it in one. That's what he was doing. And – what else did he do whilst he was "on the line", so to speak?'

Later, Roj was to insist to his audience that this debate occurred immediately before Rogan appeared, frantic and scared. In fact at least four or five minutes of inconsequential debate occurred first.

'Roj!' came a shout from the corridor of tween-cubicles, followed by the sound of pounding feet. A few seconds later brought Rogan into the cramped cubicles.

'Roj! We've got Earth on the Lowry coil! From the Department of Extra-Solar Affairs!'

In less than a heartbeat, the mission leader was on his feet and outside. Various people followed in his wake, seeking to discover what their leader was pursuing, or where he was going. One of these followers was the Doctor, who felt immensely curious about what communication might have been carried out across interstellar space.Curious, and at the same time, not very positive about the outcome.

From the humid, directed heat of ZLM Prime, the audience went suddenly into the cooler air of their Lowry shack, where the newly-uncovered HST coils had been installed.

The datastream at such a distance didn't allow a picture, so all the listeners heard was the voice of a slightly-apologetic civil servant.

'I told you, Kellerman isn't here – oh, Roj, can you take over?' said Arpad with relief. 'This mooj wants to speak to Kellerman alone.'

Roj sat in front of the microphone.

'You can't speak to Kellerman because he's dead,' intoned the mission leader flatly. 'I'll have to do.'

The circuitry and indicators showed that the line was still active, but there was silence from the other end.

'I said - ' began Roj.

'That's ….. most unfortunate, I'm afraid,' said the even more apologetic voice. 'You see, ….. Kellerman re-negotiated his contract.'

What? registered on the faces of all present.

'Ah – not with me, you understand. But still legislatively valid, and contractually binding. The relief vessel would only pick him up. Him and nobody else.'

Outrage instead of bafflement now showed on every face.

'He can't do that!' snarled Roj.

'I'm afraid he did,' said the other man. 'Sorry, but there it is. Nothing I can do. Hands tied and all that.'

What made this bad news all the worse was the bland sincerity of the semi-elevated civil servant at the other end of the endless light-years; he really did feel apologetic about the mission being dropped in it. He wouldn't lift a finger to save them, because that would violate Contract, for all his regret.

Roj vented his anger in a long bout of cursing, none of which were the officially-sanctioned swear words permitted by The Administration.

'I say, really, there's no call for …. that!' said the civil servant. 'Now, I only have this channel for another thirty seconds, so unless - '

'Renegotiate,' whispered the Doctor in Roj's ear.

'I want to renegotiate our contracts,' spat Roj

'Sorry, not possible. You see, Kellerman renegotiated ….. on the basis of sending us all your solar data. So, you see, there's no ….. for us to renegotiate or retrieve you.'

Giving up in mixed anger and disgust, Roj smashed a fist against the table, making the equipment dance in sympathy. The Doctor took this as a cue to intervene.

'Hello, to whom am I speaking?'

'Eh? You only have a few seconds - '

'Your name?'

'Oh very well. Under-Administrator of the Seventh Rank ….. Zabulon Black, of the Department of Extra-Solar Affairs.'

'Very good, Zab. I can call you Zab, can't I? We didn't get all your transmission, Zab. A phenomenon known as "drop-out".'

"Zab" remained silent, but once again the line was still open.

'In turn, you probably aren't getting all of my speech, are you? That's drop-out, Zab. If I recall correctly, and I do, because I'm a genius, there's an inverse ratio between the amount of data drop-out and the distance a Lowry coil sends the signal. For eight hundred and fifty light years you're going to lose, oh, about fifteen per cent of your total data.'

'I wasn't aware of that,' remarked Zab, sounding cautious.

'Well, your friend Kellerman wasn't going to tell you that, was he? Not if it was his ticket home.' The Doctor covered the microphone with one hand. 'Evil little git!'

'No friend of ….. I assure you. So our data – is missing fifteen per cent. Regrettable, yet still quite manageable,' replied Zab.

'Ah, you forget – the mission was sent here to get data on an unstable sun. Kellerman stopped transmitting before the flare-up. I'd estimate your data deficiency at a total of twenty-five per cent.'

'Oh,' said Zab, sounding less sure. 'That's quite a gap.'

'Then there's the alien data,' said the Doctor, allowing his voice to trail off.

'What!' exclaimed Zab. 'Alien data!'

'Yes, five years worth. Now, I'm sure our thirty seconds are up so I'll say goodbye- '

'No no no!' babbled Zab. 'Tell me more!'

'Well, what else do you need to know? Five years-worth of accumulated data, of which over half has been translated by the linguistic experts amongst the mission.'

Once again the circuit remained open, even though silent. After a long pause Zab came back on.

'It's agreed, what you have is grounds for re-negotiating. Listen, I'm going to transfer you to Contracts.'

Five minutes of chat from Roj ensured a relief starship was en route, the original contracts restored and an honorarium addded to the survivor's bank balances. The Doctor got a slap on the back from everyone in the Lowry shack, in defiance of the protocols about physical contact.

He met Rose back at the bunker, now freshly-showered, hair tied up in a bun and looking, aptly, rosey.

'Well, you might as well trade in your boilersuit.'

'Are we leaving?'

'I think we've done all we can.'

Rose looked around the big, stuffy bunker.

'Yeah. It's not like we saved the world or anything this time.'

The Doctor punched her on the arm.

'Small victories! I doubt anyone here would have survived if we hadn't turned up. Bit of a specialism of mine. Small communities under threat of siege,' he added.

Sighing, Rose collected her old clothes from a storage hamper and vanished into the bathroom to put them on. Her reappearance (in what the mission staff presumed to be the height of London fashion) meant they understood their visitors were about to depart, and the pair found themselves mobbed at the bunker entrance. Amidst handshakes and fervent thanks, Christy Taylor apologised to Rose.

'I'm sorry for being nasty to you. For a Freethie – you're alright.'

Roj overheard, and couldn't resist commenting.

'You don't know how rare that is!'

This brought the Doctor's attention back to him, and the Time Lord physically took the mission leader aside, out of earshot – not that an eavesdropper could have heard much over the enthusiastic racket their fellow staff were making.

'We come to the dark heart of your mission, Roj. The real reason for being out here.'

'Eh?' managed Roj.

'The Administration doesn't expend this kind of effort on abstract scientific endeavour, Roj. You weren't sent out here to add to the annals of astronomy, you were sent to conduct research for solar- weaponry.'

Behind them, Thijs and Kaatje were laughing uproariously at an unheard witticism from Rose. Roj's eyes widened, and the Doctor relaxed at the naievety of the big, balding man, instantly recognising sincerity.

'Weapons? Suns?'

The Doctor could have told him about the Canceller, a fission-snuffing electromagnetic monster that shrivelled stars, or the Paintbox, which turned a normally placid star into a flare-ridden planet-killer, or the Impeller, which detonated suns like burst balloons. He could have done. Instead he merely cocked his head and nodded.

'You want me to destroy that information?' asked Roj, pondering what that would do, and if it would count as revocation of Contract.

Sighing, the Doctor shook his head.

'No, Roj. Humans will need that information and the strategic systems derived from it when The Administration collapses. By that time you and the Rutans and the Sontarans will be toe-to-toe.'

Mutely, Roj eyed the Doctor. This man – no, this alien – exhibited a dislike for violence in general and a distaste for killing in particular. Quite what his reluctant acceptance of the mission's delivery of literally explosive data back to The Administration meant, Roj could only guess at. Nothing good.

Twirling the big man around by an elbow, the Doctor brought them back into the fold of cheerful people, their absence barely recognised.

'Come back and visit us sometime,' suddenly added Montag to whatever anecdote Rose had been telling them.

Rose felt her eyebrows rise. Did he mean - ?

'You're staying here?' she asked, a touch of incredulity in her voice.

'A few of us. I, for one, do not want to go back to a grey concrete box living shoulder-to-shoulder with nine billion grey people. See?'

His arms showed big, angry welts where the biometric transfers had been removed.

A TEST rat bobbed up at Rose's feet.

"Us too" it signalled, chewing on something green and crunchy.

'Well, you deserve it!' she said.

Montag offered them a lift back to the TARDIS in the sole surviving tractor, explaining that half a dozen of the elder staff didn't want to go back to Earth. Out here they had freedom, supplies, seed crops, TEST rats to sample local food and a secure bunker. Space, no pollution, blue skies, the ocean –

'What about the sun flaring up? And everything going beserk?' asked the Doctor.

Montag pointed out that they knew what to do in case of a solar flare-up: stay in the bunker. They could use pallets to block the entrance. It would be years until they needed to worry, in any case. Despite all that, life here would be miles ahead of that back on Earth.

'Kilometres ahead,' he corrected himself. 'I can say that now. In fact I can say what I want.'

They got dropped off at the TARDIS, TEST rat 10 waving a goodbye as it bobbed up and down. Rose looked around the landscape, aware of just how different it really was from the African savannah it resembled.

'I think we'll make a small detour to that moon, Elysium. There's a few aliens who deserve to be interred. Without that data of theirs nobody from the mission would be going home.'

Thus it is that an alien cemetery, on the airless satellite of a world soon to die, features five graves with inscriptions in English alongside dozens in a cursive script no longer used in this galaxy. Or anywhere else.