UNITUNITUNIT

Part Four

UNITUNITUNIT

The crisis seemed to have scaled down a notch now it was apparent that the UFO did not intend to land any time soon and a bit of time had gone by without any kind of attack being launched from orbit. Which was not to say that either of those things weren't going to happen, but they hadn't happened yet and that had to be a good thing, surely.

You could cut the atmosphere in UNIT's incident room with a knife, still, regardless. The Brigadier might as well have had that telephone surgically attached to his ear it had been so long since Sarah saw him without it.

Since nothing much seemed to actually be happening at the moment, though, she slipped out of the room to get some air and a glass of water. While she was at it she had a bit of a chat with Private Henderson, who was manning the front desk – this was his first full-scale alien invasion experience, it turned out, and he was more than a little nervous about it – but then found herself alone and at a loose end again when Benton called him over to help with something. And then the phone rang.

Sarah answered it automatically, had the receiver halfway to her ear before she remembered that she wasn't supposed to answer UNIT's phone because she didn't work there. Henderson was already hurrying back over, looking at her somewhat askance for the breach of proper military protocol, but it was a bit late to worry about that now, so she carried on, adopting her best telephone voice. "Hello, this is UNIT Headquarters."

There was a pause.

"Sarah?" The voice sounded slightly taken aback – she wasn't who he'd been expecting to pick up – but was very familiar and very welcome, to say nothing of unexpected. Sarah was so startled she almost dropped the phone.

"Harry?"

"Shall I take that now, Miss?" Henderson was asking, but Sarah barely even heard him.

"Harry, where are you, are you all right, what's happening?" The words came tumbling out, almost falling over one another in her haste. "It's Harry," she hissed at Henderson, "Go get someone!"

"Sarah, I need you to get someone there to trace this call, quickly," Harry was saying instead of answering her questions, his voice low but urgent. "I can't talk for long, they're looking for me."

"But where are you, Harry?" she impatiently repeated.

"Well, I don't know that, Sarah," he said, a note of equal impatience, or maybe just tension, drifting into his voice. "Some kind of derelict factory, by the look of it – if someone there can trace the call, maybe you can find out."

"Trace the…?" She had no idea how to do that, but looked around to see that Henderson had found Benton, and quickly called over to them, "Harry says we have to trace this call."

Benton immediately rapped out brisk instructions to Henderson, who jumped to while Benton himself held out his hand for the phone. "I'd better have a word with him myself, Miss."

But Harry was already saying, "Got to go, old girl, I think someone's coming – I'll try to leave the line open and hope they don't notice."

That was as much as Sarah heard before she handed the phone to Benton, who hurriedly called, "Dr Sullivan? Hello?" and then waited, listening intently for a moment, before shaking his head, looking puzzled. "The line's still open but there's no one there."

"He said he thought someone was coming," Sarah quickly explained. "I just hope he had time to hide."

Benton turned to Henderson. "Have we got a trace on the call?"

"Working on it, sir," Henderson reported, and he had his mouth open to add something more when a sudden hiss of static filled the air. Within seconds the noise had risen to an almost deafening pitch and Sarah clamped her hands over her ears in pain, saw Benton and Henderson shouting something at each other while doing likewise.

Then it was gone, the noise cutting off as abruptly as it had begun, although the ringing in Sarah's ears took a bit longer to subside. A moment later the radio suddenly clicked into life – the tannoy, as well – a strident, sibilant voice ringing out from every available transmitter within earshot. "Attention, peoples of Earth. This is Commander Tace of the Ataron Special Forces. There are fugitives hiding among you. Surrender them and you will be rewarded, conceal them and punitive action will be taken. You have 24 hours to comply. Attention, peoples of Earth…"

As the message began to repeat, Sarah looked at Benton and saw her own astonishment mirrored in his face. Then he started to run and she followed, sprinting down the corridors. Every device they passed that was capable of bearing a transmission was loudly broadcasting the same message. They burst into the communications room to find the Brigadier already there, barking at the operators to lock down the frequency being used.

"We can't, sir," one of the hapless operators helplessly replied. "The broadcast is overriding every protocol we've tried."

"We'll have world-wide panic on our hands if this carries on," the Brigadier shouted over the continuing broadcast…which ended even as he concluded, "Lock it down, man!" so that his voice rang out loudly in the sudden hush.

"It's stopped!" Sarah exclaimed.

"They must think we've got the message by now," Benton remarked.

"Yes, and they'd be right," the Brigadier snapped. "I want a D-notice issued to the press and a covering statement prepared. Can we reply to that message?" He turned back to the radio operators.

"I think so, sir. It might take a bit of time to set up."

While the operators fiddled with their controls and gabbled highly technical jargon at each other, the Brigadier and Benton discussed cover stories for the general public and fielded more calls from London and Geneva, and Sarah fidgeted impatiently.

Eventually one of the operators handed the Brigadier a microphone and delivered a complicated explanation about radio frequencies, transmitters, satellites and angles before saying that he thought it would work, and that the aliens should manage to pick it up if they were listening, but they wouldn't know for sure until they tried.

The Brigadier took the microphone and cleared his throat, looking awkward. "Yes, well, here goes," he muttered, before drawing himself up to his full height to speak into the microphone, crisp and clear. "This is Brigadier Lethbridge-Stewart of the United Nations Intelligence Taskforce. We have received your message and would like to negotiate. Do you copy?"

There was silence for a moment, everyone in the room listening intently. Then the Brigadier repeated his statement.

"This is Brigadier Lethbridge-Stewart of the United Nations Intelligence Taskforce. We have received your message and would like to –"

With a loud hiss of static, a large screen on the wall suddenly flicked into life, bearing the image of…an alien – a completely different alien than the ones who'd raided the place earlier. It was a fierce-looking creature with protruding brow ridges, a long hooked nose and flowing tentacles instead of hair and beard, wearing what appeared to be the equivalent of a military uniform.

"This is Commander Tace," it – he – said in a brisk, businesslike tone, while the UNIT technicians gaped and whispered 'how do they do that?' to each other. "This connection is now secure. Do you represent the peoples of Earth?"

The Brigadier floundered visibly for a moment, taken aback, but then rallied to speak into the microphone again. "Yes. Yes, I do. What is your purpose in coming here?"

Still lurking quietly at the back of the room, Sarah watched in fascination as Tace briskly announced, "This Task Force is in pursuit of a criminal gang, which was traced to your planet. Can you explain this?"

Well that put a new spin on the situation: two groups of aliens working in opposition to each other. The Brigadier certainly looked startled. "A criminal gang? Do you mean aliens – odd looking chaps wearing armour?"

"The creatures you describe are called Tyrsians," Tace loftily explained. "They have stolen valuable technology from our homeworld and we seek its return and the prosecution of the criminals. What do you know about this?"

"Only that these creatures have been making a nuisance of themselves for several days now," the Brigadier admitted, frowning. "We're searching for them ourselves."

"Then you will permit us to make landfall at once that we may conduct a thorough investigation and take them off your hands." It wasn't a request. The Brigadier bristled with indignation.

"Under no circumstances," he firmly rebuffed. "I'm sorry, I sympathise with your aims, but I cannot allow further alien incursions on this world. My organisation is already in active pursuit of your 'criminals', whose activities on this planet fall within our jurisdiction. We will liaise with you regarding the progress of that investigation, but you must not attempt to land. Is that clear?"

Commander Tace was extremely displeased. As the negotiations continued, Sarah glanced across and saw Private Henderson hovering in the doorway looking anxious as he glanced about. The Brigadier was fully occupied with his jurisdictional debate with the alien and Benton was on the phone to either London or Geneva again, keeping them appraised of the situation, so she quietly sidled over to the young private to see what was wrong.

"I need to speak to Mr Benton," said Henderson. "I've got a fix on the location Dr Sullivan was calling from."

The location Harry was calling from…Sarah realised with a start that she'd forgotten all about Harry's phone call, with everything else that was going on.

"Mr Benton's a bit tied up at the moment," she told Henderson. "You'll have to catch him as soon as he finishes his call." But who knew how long it might then take to decide on a course of action and put any kind of operation together to go after Harry and Liz, since this second group of aliens were now throwing a spanner in the works. Sick to the back teeth of waiting around for the military to get their act together while her friends were in trouble, Sarah made a snap decision. "While we're waiting, perhaps you could tell me what you've found…"

UNITUNITUNIT

UNITUNITUNIT

With their enemies hard at their heels, their ship still undergoing repairs, their stolen time travel device not fully functional and one of their prisoners having escaped, the Tyrsians were in utter disarray.

"The human will bring more humans and we have troubles enough," Tarl had bemoaned.

So Hent had been sent to search for Harry, in disgrace for having allowed him to escape in the first place, and Rahl had gone to take his place on the ship, finalising repairs there…which left Liz alone with Lewis Martin, in whose self-interest the Tyrsians apparently had absolute faith, although they did seem concerned about whether or not he'd be able to handle her for them.

"Oh, you needn't worry, she won't cause any trouble, will you, my dear," he'd indulgently declared, as if she were a good little schoolgirl, when the beleaguered Tarl expressed doubt. "We'll just push on with our work on the device while you get on with what you need to do."

Sometimes, the willingness of men to underestimate women could be an advantage. Martin also, it seemed, honestly couldn't see any reason why Liz might want to escape when she had what he saw as the opportunity of a lifetime in front of her. It seemed almost a shame to disillusion him. Almost.

While Martin fussed over the calibration of the machine, Liz hung back, surreptitiously appraising each of the several possible exits from the large workshop they were in. One was definitely an exterior door, but was also the route used by the Tyrsians to get to their ship, which meant the chances were high she'd be spotted if she made a run for it that way. Another led through to the corridor and offices where she and Harry had been locked up earlier, but Hent had gone that way to begin his search for Harry and, again, she would rather not run straight into him.

There was a third door, set into the far wall with a few old boxes piled around in front of it. Where this one led, there was no way of telling.

It was while Liz was looking across at that third door, trying to decide on the best course of action, that she caught a flicker of movement through the grubby viewing pane set into it – someone glancing through and quickly pulling back for fear of being seen.

There was only one person in the building who had any reason to hide and that was Harry.

"What is it? What are you looking at?"

Her heart sank. She'd tried to hide her reaction, but Martin had caught it anyway, and he wasn't the type to let it drop. He also had only to shout loudly enough for Hent to hear and the jig was up.

So she moved fast, snatching up a heavy Tyrsian instrument that had been left lying on a counter nearby and swinging it, before Martin had time to realise what she was doing. It connected with his head with a satisfying clunk, hopefully not so hard that it would cause any serious damage, but hard enough to knock him down and buy her a little time. As he crashed sideways into a console, stunned, Liz was already running toward that door.

It was jammed. For a long, horrible moment, she thought it might actually be locked. It was Harry she'd seen lurking on the other side, though, and he started shoving at the door while she pushed aside the boxes from in front of it and pulled at the handle with all her might. After a few frantic moments, the warped wood finally gave way and the door fell open with a terrific groan.

Would Hent have heard the noise? Would he realise what it was? How long would Martin stay down?

Liz kept moving, rather than wait around to find out the answer to any of those questions, rushing through the door and quickly hauling it shut again behind her – it wasn't much, but might slow or confuse any pursuit at least a little.

"Are you all right? I've found an exit, it's this way," Harry whispered as he guided her through a dark, murky space that appeared to have been some kind of storage area, full of mouldering heaps of discarded equipment and machinery.

Found it but hadn't taken it; he'd come looking for her instead. That answered the question she'd pondered earlier.

"I also found a working telephone in one of the offices," Harry continued as they entered what was probably some kind of loading bay, although it was hard to make out through the gloom. "So I managed to get a call out to UNIT, but I'm afraid I don't know if they were able to trace it. Still, with any luck there might be reinforcements on the way by now."

Luck wasn't something Liz liked to depend on, as a rule. "We can't rely on that," she cautioned. It was a relief to know that contact with UNIT had been made, though, that help might just be on the way already…that all of this might be over soon.

"Well, if we can find our way out of here," said Harry, "We can call again and make sure the alarm is raised."

The large double doors exiting the loading bay were quite securely fastened, however, and they weren't going to be able to break through that lock with whatever odds and ends they could find lying about the place.

"The window," said Liz, pointing. It was lower than those high windows through in the main hall and was already broken; it took only a few moments to pull some boxes over to help them climb up to it. The drop down the other side was a little steep, steep enough that she jarred her ankle quite badly as she landed, but it wasn't bad enough that she couldn't keep moving and that was all that mattered.

She drew some small satisfaction from the fact that Harry landed every bit as awkwardly as she had, his greater height affording him no advantage whatsoever where leaping out of windows was concerned.

Wherever they were, it was remote enough that there were no street lights anywhere nearby, but there was a bright moon tonight and not much cloud. That made it easier to see, to gauge their next move, but would also make it that much easier for any pursuit to spot them, so they had to move fast. They were now in a large, weed-ridden, rubbish-strewn yard, close to a drive that led to a gateway in the fence that ringed the property. The gate would be locked, of course, but they'd found their way past two locked doors already today, so sprinted toward it as fast as her sore ankle would allow.

Being long-legged, Harry moved faster than Liz and ran on ahead, which meant she had enough warning and time to skid to a halt when he was suddenly thrown back as if he'd run into an invisible wall.

"Are you all right? Whatever happened?" she exclaimed, frowning curiously at the patch of completely empty space that appeared to have knocked him down.

Harry sat up, rubbing his head. "That hurt. Some kind of forcefield, I suppose – I say, do be careful."

The warning came as she reached out, gingerly but determinedly, to feel for herself. "A forcefield, you say?" It sounded intriguing – and the crackle of energy she felt as her fingertips brushed against it was more intriguing still.

"Well, that's what it felt like," he said, picking himself back up off the ground.

"Run into a lot of them, have you?" she lightly enquired as she began to feel along that invisible barrier, up and down and to either side, to scope out the extent of it.

He huffed a rueful little chuckle. "Well, I've bounced off one or two, in my time, certainly. So what do you think?"

Taking a step back to survey the invisible wall that stood between them and freedom, just a few short feet from a break in the fence that they could have escaped through, Liz sighed. "I think that we aren't going to get through here, not while this forcefield is in place."

"No," he agreed. "UNIT will have a job getting through, as well, always supposing they've managed to track us here."

"If we can find the controls, we might be able to disable it – but we'd have to get past those creatures, and they could come looking for us at any moment." Liz glanced around worriedly. "We'll have to find cover, check out the lie of the land."

There were old crates and bits of machinery scattered all around the place, as well as knots of bramble and other weeds more than high enough to hide behind, all of which afforded them at least partial cover as they scouted cautiously around the perimeter, listening out intently for any sound of pursuit. Then, as they rounded a corner, darting from the cover of a bramble thicket to a stack of old crates, Liz was brought to a standstill by what she saw before her. Even in the gloom of night it was a spectacular sight: the Tyrsian spaceship, resting gently on a wide expanse of open land behind the building.

"My word," Harry murmured alongside her.

"Yes, quite," she fervently agreed, cautiously leaning around the crates to get a better look.

"However did they manage to land a thing that size without anyone noticing?" he marvelled.

That was a good question. "The shroud," Liz remembered. "It would have concealed their descent."

"The…what did you say?"

"Shroud – that's what they call it," she explained. "It's a piece of technology that conceals them from all – well most – scanning devices. Dr Martin mentioned it." He'd also said something else – about having to disable the shroud in order to take off because… "Harry, that's it!"

He blinked. "It is? What is?"

"Martin said they had to disable this shroud device to send out a land vehicle for the raid on UNIT, and they would have to disable it again if they want to take off because there are receptors spread around the site. Don't you see? He was talking about the forcefield we ran into; they had to turn it off to let the vehicle through – that's the shroud." Her mind was racing as she worked through the implications logically. "The receptors he talked about must be how they expand it beyond the ship to enclose the perimeter of this place. The main control would be inside the ship and we'll never make it in there, but if we can find one of those receptors…"

"We might be able to throw a bit of a spanner in the works, perhaps," Harry enthused. "Sabotage it. Jolly good thinking! Oh, hang on, what's happening now?"

They quickly ducked back behind their stack of crates, which suddenly felt a very flimsy means of defence, as both Hent and Lewis Martin came rushing out of the building, shouting agitatedly both at each other and to the rest of the Tyrsians still aboard their ship.

"I rather think your absence has been spotted," Harry murmured.

"They were already in a stew over your disappearing act," Liz told him in a low voice, watching anxiously as a couple more Tyrsians stepped out of the ship to engage in a furious debate with Hent, while Martin hopped around trying to get a word in edgeways. "They do have larger problems, though, and they'll know we can't get far, so they might not get around to launching a full scale search for us just yet – but we'll still need to move fast."

"Larger problems?"

If they moved now, would that movement be spotted, as they dashed from behind these crates back around that corner? Or were they far enough away to escape undetected? No one was looking in their direction currently, all seemingly engrossed in their argument over what to do, and it wasn't far, with thick brambles to duck behind, so if they were going to make a run for it, get well out of sight before any search could be launched, now might just be the best chance they were going to get.

"I'll tell you all about it in a minute," said Liz. "Right now, though, I think we should make a run for it, quick, while they're not looking."

UNITUNITUNIT

UNITUNITUNIT

Something was wrong.

According to the information Sarah had prised out of young Henderson, she was approaching the location Harry's phone call had come from, and according to her map there should be some kind of industrial complex there…but something definitely wasn't right because she was almost on top of it now yet she couldn't see anything.

It didn't help that it was so dark out here in the middle of nowhere – almost creepy, the area was so deserted. She'd been driving along this pot-holed little access road for well over a mile now without passing so much as a hint of civilisation, not even a lamppost to light the way.

The road ran out just as it reached a hefty-looking fence that disappeared off into the gloom in either direction. There was driveway leading in via a large double gate, which was chained shut, and behind it…?

Sarah squinted, trying to make out some kind of detail – any kind of detail, in fact.

Nothing. She couldn't see anything. There was the fence and then there was just featureless murk where the map told her a building should be.

She was definitely in the right place. There was nothing wrong with the map and there was nothing wrong with her navigational skills. It was the location that was wrong.

Leaving her headlights on to provide a bit of light, she got out of the car to take a closer look and pressed herself up against the fence trying to see. It was hard to be sure, in the dark of the night, but there seemed to be a hazy kind of quality to the air just behind the fence. Was that the reason she couldn't see any further? If only it were light enough to get a proper look.

There was a gap in the fence, just a few feet along from the gate. Sarah eyed it speculatively for a moment. She should really wait for UNIT to get here – but who knew how long that might be?

She'd been waiting for UNIT all day. She wasn't prepared to wait any longer.

She squeezed through the gap in the fence and began to hurry forward – only to collide with what felt like a brick wall and end up in a breathless heap on the floor, instead.

A forcefield. Oh, well that was just perfect.

Sarah scrambled back to her feet, grumbling to herself that she was going to have bruises in the morning, and took a cautious step or two forward, arm stretched out before her to feel for the invisible barrier she'd run into. She stopped as soon as she felt the first warning crackle of energy at her fingertips and then surveyed the scene critically. That hazy quality about the forcefield and the way it obscured her view of the building she knew lay behind it was something she'd never seen before. How it might look by light of day she couldn't tell, but as it was, under cover of darkness, if she hadn't seen the structure on the map and didn't know that was where Harry had called from, she'd have sworn that there was nothing there at all.

It was a very effective disguise. It was also a very effective barrier.

She looked around, trying to decide what to do now. There was still no sign of UNIT. At length she decided to be methodical about it. She couldn't get in and she wasn't about to turn around and go back home, so all that was left was exploring the area in search of clues or an alternate way in or something. She went back to the car and turned the headlights off, not wanting to drain the battery, fished a rather feeble torch out of the glove compartment, then picked a direction at random and started walking, staying inside that narrow zone between the perimeter fence and the forcefield.

She'd barely even started when there was a sudden snap and a sizzle as the forcefield shorted out, revealing the looming bulk of the old factory some distance behind. She almost jumped out of her skin with surprise and quickly glanced around, feeling horribly exposed all of a sudden.

There was no one and nothing in sight.

For a moment, everything was still and silent, and then loud shouting erupted from somewhere out of sight, behind the building. Not wanting to be caught out in the open like this, Sarah promptly ran for cover, diving behind a stack of crates nearby. She took a moment to catch her breath before starting to look around to gauge her next move – and felt her jaw drop open with surprise because Harry and Liz were crouched behind another stack of crates just a few feet away, staring back at her in equal astonishment.

She started to get up again to run over to them, but by then Harry was already on his way over to her, Liz at his heels. "What on Earth are you doing here, old girl?" he hissed in a piercing whisper as he joined her behind her stack of crates.

Typical Harry. Sarah rolled her eyes. "Looking for you, of course, you idiot. Why else do you think I'd be here? Are you all right?"

He looked all right, considering he'd been in a crumpled heap on the floor the last time she saw him. There was blood on his shirt and he had a few cuts on his face, heavily scabbed over, but he seemed to be otherwise intact. His brow was furrowed as if he had a headache and he looked a bit tired, perhaps, as did Liz…but then again it was the middle of the night now, so Sarah was probably looking a bit tired herself – she certainly felt it.

"Yes, yes, fine." He peered around, as if expecting to see someone else. "I say, you're not on your own, are you? What happened to UNIT?"

She rolled her eyes again. "On their way, I hope. They were a bit tied up negotiating with the Atarons when I left?"

Harry frowned. "Negotiating with the what?"

"Atarons," Liz chipped in, "The other aliens, the ones who are looking for this lot. I did tell you about it, if you remember." While Harry murmured, 'oh yes, that's right', Liz turned to Sarah. "Have they made contact with UNIT, then?"

"Sort of," Sarah explained. "They sent out a kind of global broadcast to demand we surrender the fugitives they're after, and the Brigadier got his communication people to reverse the call, so to speak. They wanted to send a search party down and he was trying to stop them."

"I see." Liz glanced around worriedly. "Well, we can't stay here. The Tyrsians know we've escaped and they know the forcefield is down: they'll be panicking."

"Yes, what happened to the forcefield?" Sarah wondered. "It was there one moment, gone the next."

"Oh, that was Liz," Harry told her, "Sabotaged one of their receptor thingies – dreadfully clever."

"It won't be so clever if they find us here," Liz pointed out. "Is your car nearby, Sarah?"

"Yes, it's just back that way…" Sarah began, but her voice trailed off as she realised that returning to her car would take them nearer to where the aliens, the Tyrsians, had gathered to loudly discuss the malfunction of their forcefield; they were still out of sight, around the corner of the building, but she could hear them ranting from all the way back here. "I don't think they'll see us if we run for it," she hesitantly offered, wishing she could be certain.

"But we'll need to move fast," Liz nodded. "Come on."

"Wait, listen," Sarah hissed as a sound caught her ears.

"Engines," said Liz, listening intently.

Harry lifted an eyebrow. "Our UNIT reinforcements, perhaps?"

"Well, I should hope so," said Sarah. "It's about time they got here."

In no time at all, the night was lit up by headlights as a collection of UNIT vehicles bore down on the site and came to a halt just outside the fence, close to where Sarah had left her car. A squad of soldiers jumped out and started cutting through the fence to gain access.

Liz sighed and shook her head. "They don't believe in subtlety, do they?" she muttered. "For all they know, they could have signed our death warrant, announcing their arrival like that."

"We'd better let them know we're here," murmured Harry, but before they could move to join their colleagues, the Tyrsians appeared around the side of the building – and started firing at the UNIT troops. The troops promptly fell back and returned fire and that was the end of any hope they had of dashing the hundred or so yards that separated them from UNIT's protection, as they would have to enter the field of fire to do so. All they could do was sit tight and wait for the shooting to stop.

A stray blast from one of the Tyrsians caught one of the crates at the top of the stack they were sheltering behind, and Sarah couldn't quite hold in a yelp as it missed her head by no more than a couple of inches.

"Over there, quick," Harry urged and the three of them ran, stooping low for whatever shelter they could find behind thick brambles, and flung themselves behind another heap of junk, nearer to the building but slightly safer from the ongoing gun battle.

From here, Sarah could just about make out the tail end of the Tyrsian spaceship, parked on the ground just around the corner. A cluster of Tyrsians was gathered around it, focused intently on their battle with the UNIT troops, and behind them…

"Who's that?" she wondered. There was a man, a human, sneaking away from the Tyrsian line, keeping tight to the wall.

She assumed at first that he was another prisoner, trying to escape, but Liz frowned and said, "That's Dr Martin – what's he up to now?"

"Perhaps we should find out," Harry suggested.

Liz nodded. "Yes, perhaps we should."

The man – Dr Martin – had entered the building via a side door not too far from where they were hiding…not too far from where they were hiding, but they still had to leave that hiding place and dash across alarmingly open ground to follow him, with a gun battle raging nearby. They waited for a slight lull in the shooting before risking it, but even so, Sarah's heart was pounding like a jackhammer as she sprinted across those few yards, expecting to be hit at any moment. As soon as they were inside, she immediately felt safer. Just having the noise of the gunfire muted slightly was a relief.

There was no sign of which way Dr Martin might have gone once he entered the building.

"He'll have headed back to the hall," said Liz, "To check on the device."

Harry nodded. "Yes, I'd imagine so – it's this way. I think."

"Wait, what device?" Sarah wanted to know as they cautiously made their way through the dark, musty hallway.

"A stolen time travel device," Liz told her.

"One they don't even know how to work properly," added Harry.

"A time travel device?" That…made sense of so many elements of the case that had been puzzling Sarah. "That would explain Tom, then," she mused – and then had to explain who Tom was and where he came from.

Harry had been leading the way, but came to a standstill as the corridor branched off in two directions. "I think it's this way," he said, looking uncertain. "But I'm afraid I'm not entirely sure."

Liz frowned. "Yes, I think that way as well, but we'd better be certain. Perhaps we should split up. You two carry on down there, and I'll have a quick look this way, to be on the safe side, and then catch up to you."

It seemed a reasonable plan. Sarah and Harry continued along the murky hallway, and within moments Harry was looking more assured. "Ah yes, this is starting to look a bit more familiar. I believe the main hall should be just through here."

"Careful," Sarah warned as he reached for the door. "We don't know what's in there."

He was very cautious as he pushed the door open just a fraction to peek through into the room beyond

"I don't think he's here," he murmured as he pushed the door a little wider and very warily stepped through. Sarah followed, looking around with interest as she found herself in an enormous room that must have once been the factory floor, now derelict and deserted, empty save for an assortment of weird-looking machinery over against one wall. There was no sign of Dr Martin.

And then, all of a sudden, there was. The man popped up from behind a console like a jack-in-the-box and jabbed frantically at the controls.

There was a brilliant flash of purpley-blue light and a surreal sensation of being pulled off her feet…followed by darkness.

On to Part Five