Part Three

"'Lieutenant' is an archaic rank," Vishinsky remarked, apropos of nothing but with a note of challenge in his voice, as he led Harry through a maze of corridors aboard the space probe, which had much the same utilitarian feel about it as the survey team's base: metal floors, bare walls and security doors at every junction, all very functional, nothing of ornament whatsoever.

Harry opted not to rise to the challenge since, thirty thousand years down the line and all that, the man probably had a point.

"Well, I suppose I'm an archaic sort of chap," he said. Sarah certainly seemed to think so.

"You're from Earth, you say?"

"That's right."

"You're a long way from home. And your rank is military." Vishinsky paused halfway through a door and narrowed his eyes to regard Harry intently. "But your companions are civilian. How do the three of you come to be out here in deep space, so far from your unit?"

They were a good sight further from home and UNIT even than Vishinsky knew.

"I sometimes wonder that myself," Harry muttered under his breath, and then saw the look on the other man's face and hastened to deliver a more appropriate response. "I'm seeing the Doctor back to base, Commander…the long way, it seems. Er, is this it?"

He stepped past Vishinsky into the probe's med bay, which was large, bright and functional, full of unfamiliar equipment, the two corpses from the survey team base already here, brought on ahead by Salamar's navvies. It also contained something rather more unexpected.

"I say, that's the TARDIS!" Harry had known it had been captured, of course, but hadn't expected to find it here. He also hadn't expected to find it locked away behind some kind of forcefield: a shimmering, iridescent barrier.

"The box is yours." Vishinsky followed him across the room and watched, inscrutable, as he pressed his hands against the forcefield – simply had to try it, couldn't resist. It tingled to the touch, an impassable obstacle.

"Well, it belongs to the Doctor," said Harry, stepping back in defeat. They were going to have to prove their innocence to get it back.

Or find the control panel, perhaps.

This was Vishinsky's first sight of the TARDIS. His forehead crinkled, head tilting to one side to regard it with outright perplexity. "What is it? Some kind of capsule – for storage, perhaps, is this where you keep your weapons?"

Was that honestly what he thought? Harry had thought Vishinsky was coming around to believing them, but clearly he was not yet convinced – the accusation was half-hearted, perhaps, but the suspicion remained nonetheless.

"Our vehicle, in point of fact." Harry felt rather as if he were walking on egg shells. How on Earth did one explain the TARDIS? He turned his attention to the corpses instead, hoping they might be simpler to deal with. He knew where he was with a corpse. "Er…shall we begin?"

Vishinsky seemed willing enough to leave the subject, for now. "We'll start with these two," he agreed with a nod. "Bartrum's body hasn't been retrieved yet."

His detachment was almost clinical, but anger at the loss of a crewman glinted in his eyes. Harry looked down at the two dead scientists.

"I'd rather a live patient, any day," he admitted. "Do you know their names?"

"Why?" Vishinsky was surprised by the question.

"Well, they were people once," Harry pointed out, remembering the graves they'd dug for their comrades, no one left to do the same for them. "We may have been too late to help them, but I should like to know who they were."

Vishinsky seemed to appreciate the sentiment. "According to the roster the female is Lake Alberg and the male Roman Aziz. Alberg was a geologist, Aziz the team's exographer."

"Lake Alberg and Roman Aziz." Rum sort of names these Morestrans had. "Right then…er…"

Looking around for the tools he'd need, Harry hesitated, suddenly realising this wasn't going to be quite as straightforward as he'd hoped. Archaic was the word, all right. An autopsy should be a simple enough procedure – would be if this were anything even remotely resembling the hospitals he'd trained at or the sick bay he presided over at UNIT, thirty thousand years ago…but it wasn't. They called it a medical bay, but it was all computers and electronic gizmos and gadgets and whatnot – thirty thousand years of medical advances and not so much as an instrument tray anywhere in sight.

Vishinsky was already moving toward a rather fearsomely high-tech device at the head of the nearest cot, flicking a switch to activate the equipment. "A full bio-scan should give us all the information we need, don't you agree?"

"That was what the Doctor suggested," Harry recalled, heart sinking. He could examine a body and he could dissect a body, but the technology for a 'bio-scan' had not formed any part of his medical training!

Rum sort of a doctor he'd look, not knowing his way around a sick bay, when the position here was already tenuous and it wasn't just his own future at stake, but Sarah's and the Doctor's, too – Vishinsky barely believed their story as it was.

"Here we are then." Vishinsky waved for Harry to proceed.

If in doubt, the Doctor would bluff it out, always did. Not knowing what else to do, Harry crossed his fingers and sought refuge in hearty, pompous affability. "Well, this is your sick bay, Commander, I don't want to intrude. You go ahead and take the lead on this. I'll assist…"

dwdwdwdw

Captain Salamar waited for full daylight before sending Sarah out with a pair of guards to retrace her steps back to the plateau where she'd last seen Professor Sorenson, his manner high-handed enough that she felt her hackles rising and had to remind herself that she wanted the mission. Sorenson's evidence was crucial: both to clear her name and get to the bottom of whatever was going on here.

Daylight on Zeta Minor was dull and orange, casting a fiery glow across the gleaming metal surface of the space probe as they passed. Sarah wondered how Harry was getting on in there – hopefully better than the Doctor and Samina Landa were with their so-far futile efforts to restore power to the base, which had the Doctor in a high old dudgeon: torn between fascination with a problem that defied resolution and frustration that he couldn't find a solution anyway. He'd been up to his neck in cables when she left, muttering to himself about relays and back-ups, so absorbed in the problem he barely even noticed her go.

The guard called Wijaya turned to her as they stepped past the probe into the forest, his brightly-coloured head tilting quizzically and his dark brown eyes glinting with mischief.

"Lead on, o guide," he said with a saucy wink. "Watch out for ghosts!"

"Don't start," warned his colleague with the air of one who knew his ways of old, her blue-grey eyes scanning the tree cover warily. Wijaya laughed, stroking at the narrow black goatee that ran in a thin line down the centre of his chin and sideways along a strong jawline; he was handsome and he knew it, always the worst kind, his manner relaxed and teasing.

"Don't tell me you believe in invisible monsters, de Haan?"

"It doesn't matter if you believe in them or not," said Sarah, annoyed by his flippant attitude on top of everything else. "They're just as real, either way."

Wijaya shrugged, unconcerned. "I'll believe it when I see it."

De Haan was a tall, athletically-built young woman with thick chestnut hair drawn back into an untidy chignon, a few wispy curls straying loose around her temples. She rolled her eyes eloquently and caught Sarah's eye. "That's the point, isn't it – if they're invisible you won't see them. Not till it's too late."

"Oh, so you do believe in ghosts," Wijaya teased as Sarah led the way deeper into the forest, trying to remember the right direction to take.

"I believe something killed Bartrum and those scientists," de Haan retorted, and he sobered at once, whether at the thought of ending up like that himself or at the reminder of the crewmate they'd lost.

With sunlight filtering through the tree canopy, the vines and fungi lost their luminescent glow, but the mud underfoot remained just as viscous. Sarah gritted her teeth and tried not to think about the nice solid roads and pavements of London, where the Doctor was supposed to have taken them; she'd known they were never going to go straight there and had delighted in the thought of it, the excitement of setting out for an unknown destination and exploring a new world. Boggy ground and spoiled boots were a small price to pay…even if it didn't feel that way after spending half the night trying not to get stuck in the mud.

Staying alive, now, and keeping everyone else alive, solving the mystery – that was the thing.

Behind her, de Haan picked her way along stoically enough while Wijaya's studied air of light-hearted nonchalance gradually faded to disgruntlement.

"So much for a nice boring charting mission," he grumbled just as Sarah heard a sound up ahead and stopped dead in her tracks, trying to listen.

"Did you hear that?"

"One of your ghosts?" he teased.

"I don't think so." Wijaya might think it all a big joke, but Sarah knew otherwise. There was no crackling sound, no chill in the air, this wasn't the same thing she'd experienced earlier, but she'd definitely heard something. "There's something moving – coming this way."

De Haan pushed alongside her, be-freckled snub of a nose crinkling as she frowned in concentration, head tilted to listen. "Over there!"

She stepped forward, reaching for her gun, and Wijaya too was suddenly all business, humour and scepticism forgotten as he moved in front of Sarah like a human shield, weapon in hand, shouting, "Who goes there?"

They waited, tense, listening to the rustling of foliage and slapping of footsteps through thick mud, growing closer and closer…until at last a bulky figure swept into view through the trees.

"'Who goes there' – how dare you! Who goes there?"

Sarah breathed again. "Professor Sorenson! It's all right, it's the professor."

"And who might you be?" he grumbled with a scowl.

"It's Sarah, Professor. Sarah Jane Smith – don't you remember?" She felt a pang of doubt – if he didn't remember her, failed to back up her story, would that place her back in the firing line for Bartrum's death? Would the rescue team fall back on accusing the easy suspects once more and give up the investigation completely – until more people died?

Sorenson squinted at her.

"Oh yes. You," he said, and she let herself relax again. "But what's all this? Where've you all come from?"

"Senior Ensign Carly de Haan, Professor Sorenson – this is Ensign Eslam Wijaya." De Haan stepped forward, holstering her weapon, and held out a hand in greeting. "We're with the space probe KX9-06. We were diverted to check up on your team, Federal Council were concerned that contact had been lost. Are you all right?"

Sorenson peered vaguely at her outstretched hand but did not take it.

"Then this is a rescue," he muttered to himself. "Not here to steal. Yes, yes that's right, that's what was needed. I'm ready now."

De Haan was confused by this rambling reply. "This is a rescue mission sent by Morestran Federal Council, yes. We're here to take you home – are you all right?"

"Oh yes," he repeated, and he did seem to be more lucid than when Sarah had seen him last, even if his attention was rather scattered still. "Yes, the days are quite safe."

"We need to escort you back to base, Professor," de Haan continued. "Captain Salamar wants to talk to you about your team."

"Team…my team." Sorenson seemed almost to shrink into himself and blinked at her in apparent confusion. "Aren't they there?"

De Haan was taken aback. She cast worried side eyes toward first Wijaya and then Sarah, and carefully asked, "You think your team is at the base, Professor?"

"He knows they aren't," Sarah murmured, remembering those graves, his reaction when she'd spoken Evan Danziger's name aloud. He'd told her there was no one left but him, he couldn't have forgotten. Could he simply not face the truth in the cold light of day?

He twisted his hands together in agitation, muttering, "Alberg is there – should be there – Aziz returned to base, he – he was suffering from fatigue. He'll be fine now."

"When did you last see Aziz?" Wijaya pressed. "What happened to the others? There were eight in your team."

De Haan shot a warning glance at him, hissed, "Leave it to the captain, Eslam," but it was too late, Sorenson became deeply distressed.

"We've had difficulties. Conditions are hard," he muttered, wringing his hands, his gaze darting all over the place as if he couldn't bear to make eye contact. "We've lost some…we lost them…but the important thing is the mission has been a success. We found what we came to find." He blinked and shook his head distractedly. "Yes. No, its fine, the mission was a success. It's not far."

He plunged away, heading in the direction they'd just come, back toward the base, and all they could do was follow.

dwdwdwdw

The bio-scanner and associated technology in the KX9-06's medical bay was astounding, beyond Harry's wildest dreams – in fact, trying not to exclaim with delight at what it could do was almost harder than surreptitiously prompting Vishinsky to show him the ropes without giving himself away.

Almost.

He rather thought he might actually be pulling it off, observing and learning…until Vishinsky asked him to pass the neurolyte probe and he had no idea what that was.

Harry panicked, selected a tool at random more in hope than expectation, knew at once that he'd chosen wrong and tried to bluster his way out of the mistake…but it was no good.

"You're a terrible liar, Lieutenant," said Vishinsky, deadpan, and just like that the jig was up.

It occurred to Harry that his mother would have been delighted to hear this assessment of her only son, but for a professional working in the security services, sometimes called on to operate undercover, it was rather a damning indictment.

"Yes," he said with a sigh. "I know."

Vishinsky had a marvellous poker face, utterly unreadable.

"I can't make you out, Sullivan," he said, steely gaze fixed on Harry's face. "You know your medicine, right enough, but you can't tell a neurolyte probe from a dermal bond unit, can you?"

The Doctor would have got away with it, Harry was sure – but then again, the Doctor would have known where he was with this technology to begin with, no pretence necessary. He still didn't see what else he could have done but play along, in the circumstances, but also didn't know what he could say now that wouldn't compound this failure, that would convince the commander of their innocence and benign intentions.

Sarah and the Doctor were relying on him. And the truth was all he had.

"I'm sorry, Commander," he said. "You're right. I am a doctor…but your technology is a bit beyond me, I'm afraid."

Vishinsky's eyes narrowed still further. "I thought you said you were from Earth."

"I am from Earth," Harry helplessly insisted. Just not the Earth Vishinsky would assume.

Vishinsky studied him for what seemed an age, brow crinkled in thought…but then shrugged as if this was all he'd needed to hear.

"I knew Earth was a backwater, but I hadn't realised Morestran medical technology had deviated so far from central standard," he said. "Why not simply say so from the start?"

Was that it? Harry could have kicked himself – if a technological divide between Earth and the Morestran Federation was so readily believed, he needn't have put himself through all this in the first place.

"I'm sorry," he said again, with chagrin. "If you ask Sarah, she'll be quite happy to tell you what an idiot I am. I'm afraid I panicked rather when I saw all this equipment, after the Doctor had told you I could help. You already suspected us of murder…"

Vishinsky snorted, looking almost amused.

"I don't know who you people really are, Lieutenant, or what you're doing here, but you didn't kill these people. I don't know what did, but that Doctor of yours is right." He turned back to the corpses, shaking his head. "Nothing human could have done this."

"No." It came as a relief to know that at least someone believed them. The Doctor had said Vishinsky was a reasonable man and this was what he meant – Harry rather envied that ability to judge a fellow so accurately, within minutes of meeting him.

"You may not be familiar with our technology, doctor," Vishinsky added, "But you've made more sense of these findings than I have. So let's finish this."

dwdwdwdw

Sorenson possessed a rare turn of speed, Sarah already knew that from their earlier meeting, and again she had to trot to keep pace with him, wishing for longer legs, as he dashed out of the tree cover and charged across the glade, barely sparing a glance for the probe as he passed, calling loudly for his former teammates.

The Doctor was outside the base, perched on tiptoes on a narrow window ledge to work at full stretch on the connections to a panel on the roof. Distracted by the sudden tumult, he lost his footing and fell, landing on his back in the scrubby underbrush that surrounded the building. Already running at full tilt after Sorenson, Sarah changed direction mid-stride.

"Doctor!"

The Doctor, however, was not the slightest bit interested in being helped back to his feet…or, indeed, in the minor fact of his having fallen in the first place.

"Was that Sorenson?" he demanded, lunging toward the door. "Quickly, Sarah!"

Hurrying into the base, they almost ran into the backs of de Haan and Wijaya, who'd stopped dead because Sorenson had stopped dead, staring numbly at Landa, who was working at the control panel, and Salamar, who was hovering fussily at her shoulder.

"Aziz," Sorenson whispered. "Alberg. Where are they?"

Salamar eyed him severely.

"Professor Sorenson, I presume," he brusquely observed. "We've been waiting to speak to you."

Sorenson's mouth opened and closed a few times.

"They're gone," he managed at last, half-turning, his haunted eyes darting around before focusing on Sarah with something that looked like mute appeal. "All gone."

"I know. I'm sorry." She impulsively pushed forward to take his hand, full of sympathy for his broken state.

"Can you tell us what happened to your team, Professor?" the Doctor gently asked.

Sorenson twitched. "Alberg was here, she was compiling reports. Aziz returned to base…"

He faltered and trailed off, and Salamar huffed with frustration.

"Professor Sorenson, I am Captain Salamar of the space probe KX9-06," he rapped out in cold, brisk tones. "Morestran Federal Council were concerned that contact with your team had been lost –"

"So you were sent to check on us," Sorenson unexpectedly finished for him, indicating de Haan. "She told me."

Salamar was flustered by the interruption – and was annoyed by his fluster, visibly frustrated by his inability to impose his authority and control on the situation. "Professor, we arrived to find Aziz and Alberg dead alongside the graves of the rest of your team. You are the only survivor. Can you explain?"

Again Sorenson's mouth opened and closed, like a goldfish gasping for air.

"The mission. My mission…" he stammered at last, blinking. Then he rallied, an almost manic gleam in his eye. "My mission is complete, Captain – the breakthrough was made only in these last days, a discovery of tremendous importance. We found what we came to find."

"And what was that, Professor?" the Doctor asked with great interest. "What were you looking for? What did you find?"

"Don't answer that question," Salamar immediately snapped, eyeing the Doctor distrustfully. "Perhaps we might return to the probe, Professor, and continue this interview in private."

"What? No, wait," the Doctor protested. "I must speak to the professor, it's vitally important that we find out –"

"No, Doctor," Salamar insisted, a glint of vindictive satisfaction creeping into his cold blue eyes. "Your assistance with the professor's de-brief is not required. Come this way, Professor Sorenson."

He ushered the bewildered Sorenson away with a final glare at the Doctor, who sighed.

"The fool," he growled under his breath, hurrying after them. "Captain Salamar, I must talk to the professor – you don't understand how vital it is."

"No, Doctor, you don't seem to understand how vital it is," Salamar snapped. "Professor Sorenson's mission here is top secret – certainly not for the likes of you. You are on probation, if you recall, and your innocence has not yet been proved. You will remain here and continue working – stay with him, Landa. De Haan, go to med bay and tell Vishinsky I want to see him in my quarters immediately. Wijaya, with me."

He swept Sorenson away, de Haan and Wijaya at his heels.

The Doctor stared after them, looking thoroughly disgruntled. "Do you know, Sarah, there's just no helping some people. Did Sorenson tell you anything?"

"Not a lot," she admitted. "Nothing you haven't heard for yourself just now."

His elastic face contorted in a grimace of frustration. "Well, perhaps the survey team's logs will prove a little more enlightening. I think we're almost there now. Did you find that mag-lock coupler, Samina?"

Landa stepped forward with a tool in her hand and a thoughtful, closed-off expression on her face. The Doctor took the tool and clambered back up onto the window ledge to resume his work, and it was Sarah's turn to sigh in exasperation, wondering what he expected her to do now. Stand around and watch him work, probably.

No chance.

"I'll go and see how Harry's getting on, then, shall I?"

There was no reply, not that she'd expected one. Typical Doctor: lost to the world when his head was buried in a project. Sarah poked her tongue out at his back and headed for the probe, wondering how she was actually going to find her way to the medical bay to check up on Harry.

The problem was solved almost immediately when she saw that de Haan had stopped just outside the probe to re-fasten a boot.

"Mind if I tag along?" Sarah brightly asked.

De Haan was dubious. "I don't know if I should…"

"Oh, go on," Sarah wheedled. "What harm could I possibly do?"

De Haan tilted her head and pursed her lips, then suddenly smiled, jerking her head for Sarah to follow her aboard. "Come on then, before the Captain sees you."

"He's got enough on his plate without worrying about me," Sarah diplomatically agreed, not liking to say that he seemed a little out of his depth, although from the look on her face de Haan might agree with that sentiment.

"This is not what any of us were expecting from this mission," she carefully replied, leading the way along a series of dull, featureless hallways.

"You said you'd been diverted," Sarah remembered. "Was it far out of your way?"

"Pretty far," said de Haan. "And hard rations all the way; we're not really provisioned for a push this deep, but we were the nearest, so. No one comes this far out if they can help it – there's no telling what might be out here."

No telling what might be out here. Did that mean…? "You believe us, then?"

De Haan regarded her solemnly. "Do I believe that an unexplored planet on the far edge of the known universe might hold hidden dangers? Yes, Miss Smith: I do."

"I wish your captain felt the same way," Sarah told her with feeling. "It's Sarah."

De Haan smiled. "Carly. Here we are."

Following the other woman into the medical bay, Sarah was relieved to find that there was nothing grisly on display. The room was light and bright, packed with computers and all kinds of high-tech equipment – not the slightest bit like Harry's sick bay back at UNIT, yet he seemed perfectly at home, head bent over a display on a screen, discussing the read-out with Vishinsky, so engrossed that neither noticed the new arrivals at first.

Strangely enough, the TARDIS was also there, every bit as incongruous as it had looked in the Doctor's lab back on Earth. Sarah stared at it in surprise as de Haan delivered her message.

"Sorry to disturb, sir – we've located Professor Sorenson. The Captain would like you to join them in his quarters."

While Vishinsky grouchily responded, Harry noticed Sarah for the first time and leapt to his feet with a big smile, hurrying over to greet her. De Haan departed with a friendly grin and Vishinsky, looking harassed, scuttled off to see what the captain wanted, muttering that he wouldn't be long, but Sarah was still more interested in the TARDIS, locked behind a shimmering barrier – fat lot of use it'd be to them in there.

"So that's where it went," she said as soon as she and Harry were alone.

"Is that a forcefield?"

"Quarantine field, according to Vishinsky," he cheerfully replied, in the rather pompous tone he liked to use when he was pleased about knowing something she didn't. "I believe it's operated from one of those panels over there, but they've not shown me those controls, obviously."

"Obviously. The Doctor would know. If he was here we could just jump back in and go: leave them all to it," Sarah said, knowing it was never going to be that simple and asking herself if she'd ever really want it to be. There was a mystery here, just waiting to be solved, and she wanted to know what the answer was.

"That'll be the day," Harry retorted with a rueful grin.

"Won't it just! Well, at least we know where it is when we need it. How are you getting on with all this…?" She waved her hands around the room, failing to come up with an appropriate description for all this, "This."

It was the wrong question to ask. Harry promptly started bouncing all over the place, showing her various pieces of equipment and trying to explain what they did, positively bubbling over with enthusiasm for the marvels this advanced medical technology was capable of.

Sarah laughed. She didn't often see this side of him – it was rather sweet, even if she barely understood a word. "Harry, are you trying to tell me you actually know how to use all this?"

He flashed a grin that was pure schoolboy. "Of course not, old thing – but Vishinsky does. Look, we've nearly finished here. Tell the Doctor I'll pop back over to update him in a jiff."

With Vishinsky now otherwise occupied, Sarah might have offered to help, except she'd already had her fill of playing nurse to Harry's doctor back on Nerva Space Station. She took his advice instead, swatted his arm for the 'old thing' and headed off…only to find a guard at the main exit, who glowered at her on sight.

"You're not supposed to be wandering around."

"Really? No one told me," Sarah pertly replied. The man was not amused.

"Where do you think you're going?"

"Over there." She pointed out through the open door. "Back to the base."

"Quickly then – and stay there," he snapped, standing aside to let her pass, and when she glanced over her shoulder she saw that he'd gone straight to a wall-mounted communication device just along the hallway – informing the captain, perhaps. Whatever happened to that cooperative spirit of investigation?

There was a chill in the air as she stepped outside the probe, her breath misting in the air despite the warm sun riding high in the sky. She stopped in her tracks expecting the worst, goose-bumps pricking at her skin and breath catching in her throat because she knew now, she'd seen those corpses…

But there was no crackling sound this time. The chill faded.

Sarah breathed again. Had something passed by without attacking? Or was her imagination playing tricks on her?

Better safe than sorry. She hurried on into the base, calling out, "I think we've lost Harry to medical science," as she entered, and then saw that the Doctor had the computer working at last. "Hey, you've got the power back!"

"Well yes, but then again no," he rather vaguely replied, and then completely failed to elaborate, attention focused on the screen before him.

"We tried connecting a spare power cell from base stores, but found it had also been drained. Both are now linked in and charging," Landa helpfully explained, hovering at his shoulder looking brisk and efficient. "But not to anything like full capacity. There's no fault that we can find, if I didn't know better I'd say something was drawing the power off –"

"Something is drawing the power off," said the Doctor without looking up. "But we can worry about that later. By piggy-backing the two and boosting the gain there's just enough charge now to give us access to the mainframe and that's all we need. What was that about Harry?"

"He'll be over in a minute," said Sarah, peering over his shoulder for a look at the screen that had him so engrossed. "What've you found?"

"The answer," said the Doctor, looking grim. "Although of course these poor souls didn't know it at the time."

dwdwdwdw

Sending Sarah back over to the base without him had been a mistake, Harry realised when he tried to find his own way back and became hopelessly lost the moment he set foot outside of the medical bay. Vishinsky had been talking when they came, so he'd not paid much attention to the route – had they approached from the left or the right…?

"Oh good job, Sullivan," he muttered to himself, looking up and down the featureless corridor and spotting no landmarks for navigation whatsoever. First the tangle over unfamiliar medical equipment and now this – fine work he was making of the mission!

"Did you cut him open?"

Harry startled at the unexpected question and span around to see the young man who'd captured Sarah standing along the hallway eyeing him moodily.

"Sorry, old chap, didn't see you there. It's, er…" Dash it, what was the name again? "Sub-ensign Utoblo, isn't it?"

Utoblo nodded. "Leo Bartrum," he said, a note of urgency in his voice. "We brought his body back. Did you cut him open?"

Another haircut that would have been strictly non-regulation in Harry's day, and the lad barely looked old enough to shave. You knew you were getting old, Harry told himself from the lofty vantage point of approaching 30, when recruits started to look so dreadfully young.

"No," he said and watched as Utoblo's taut posture relaxed very slightly, relief coming into his eyes. This mattered to him. "No, there was no need. He was a friend of yours, was he?"

"You could say that." The lad studied his shoes. "I don't like to think of him cut open in there."

That sort of friendship, perhaps – Harry'd attended an all-boys boarding school and then joined the Navy; he'd grown rather good at spotting the signs. He fumbled for what to say now. "Er…would you like to see him?"

Utoblo shook his head, lips pressed tightly together. When he spoke his voice was low, tightly controlled. "I already saw him. In the woods. Did your people do it?"

He'd been quick to accuse Sarah earlier but seemed more upset than hostile now.

"No," said Harry.

"Do you know what did?"

"I'm afraid not." Harry did, on the other hand, suddenly see a way out of his current predicament. "I do have test results, however. Perhaps you might show me back over to the base…?"

Having a guide made all the difference. They made it to the exit in no time and stepped outside to find the Doctor having a blazing row with a guard at the door, Sarah at his shoulder looking annoyed and the technician called Landa stood to one side, determinedly not getting involved.

"For heavens' sake, man," the Doctor boomed. "You don't understand –"

"I understand my orders," the guard stolidly replied. "You people are not to move around."

"Since when?" asked Utoblo from behind him, all innocence and bewilderment – not up to speed on the latest orders, clearly.

The guard hadn't heard them approach and startled.

"Since the captain said…" He broke off as he spotted Harry and all but growled in exasperation. "That one's not supposed to be wandering around either!"

"Then perhaps you should have put a guard on the infirmary," Harry mildly suggested, wondering what had gone wrong now. "What's going on?"

"Yes, why are we being penned up?" Sarah hotly demanded. "We haven't done anything wrong, we're been helping with the investigation – what's changed?"

"The captain's been having a cosy little chat with Professor Sorenson. I imagine that's what's changed," the Doctor darkly remarked, and Sarah frowned, turning puzzled eyes toward Harry, who couldn't honestly say he was any the wiser than she was.

"What difference does that make? We have new information," she told the guard. "We must see the captain."

"The captain's busy."

"He'll be busier still if he doesn't make time to hear what I have to say," the Doctor warned.

"He's not to be disturbed, he gave strict orders."

The Doctor eyed the man appraisingly. "What's your name?"

"Harlow Ponti," replied the guard, warily, as if he feared it may be a trick question. A tall man with a thin, wiry build and a neatly trimmed beard, the rich brown of his skin contrasting starkly with the bright white trim of his uniform, he was smart, officious and unwilling to budge an inch, because orders was orders. Harry knew the type well.

"Mr Ponti, eight people have died on this planet and there will be more deaths to follow if we don't act now," said the Doctor, his most charming, persuasive tone laced with urgency. "Now, you can sit back and allow that to happen, and comfort yourself that you followed your orders to the letter…or you can open your mind and try thinking for yourself. Make a choice. Take a risk that might just save the lives of your comrades – perhaps save your own life. Call the captain. Tell him we need to speak to him, urgently. We'll just wait right here."

He made a big show of planting his feet on the ground and stuffing his hands into his pockets to demonstrate that he had no intention of budging so much as an inch until his request was granted.

Ponti glowered at him morosely but at last let out a sigh of defeat.

"I can call through to Command and leave a message for when the captain is free," he suggested, and stomped back into the probe wearing a disgruntled expression and the long-suffering air of a man who felt deeply put-upon.

Harry looked to the others, confused still, because they'd all agreed to cooperate, hadn't they? "What's brought all this on, then?"

"Sorenson's a fool," said the Doctor, as if this explained everything. He began pacing impatiently around. "No sacrifice too great in the pursuit of glory. Never mind the lives when there's mineral wealth to be harvested, a new resource to fuel a depleted homeworld – and a hero's welcome for the man who made it possible, working on while his team were slaughtered around him."

"But he was so upset," Sarah protested.

"Guilt," the Doctor snarled. "It's all there in the log. He forbade his team to call for help because he thought he was onto something – by the time Alberg broke rank it was too late. Never mind the implications, the consequences – blind idiocy – and now he has the captain's ear, and Salamar's fool enough to fall for it."

This last was almost spat at Landa and Utoblo, neither of whom seemed to know what to do. Right or wrong, Salamar was their captain, after all.

"Fool enough to fall for what, exactly?" Harry began to ask, before the other thing the Doctor had said registered. "Hold on, what was that about minerals?"

"That's what this is all about, apparently," Sarah explained. "It's what the survey team were looking for – what they found."

It also struck rather a chord. Harry held out the fistful of print-outs he'd brought over, courtesy of Vishinsky, who'd shown him how.

"The thing is, you see, we picked up some sort of residual mineral trace on a kind of tissue profile of the victims," he explained, sure it must be relevant somehow – too odd not to be. "Marvellous technology, I must say. Wish we had it in my day!"

The Doctor took the papers, teasing, "You're glad you came now, aren't you, Harry?" with a cheeky wink.

Harry opted not to rise to the bait.

"Traces left at a micro-cellular level," the Doctor mused, leafing through the report with Sarah peering over his shoulder. "That's very interesting…"

"Couldn't identify the substance, though, I've never seen anything like it – and neither had Vishinsky," Harry added, well aware that, as a native of this time, Vishinsky's inability to identify the mineral traces carried far more weight than his own.

"I'd be surprised if you had," said the Doctor.

Harry waited for a moment to see if he'd elaborate, but nothing seemed forthcoming so he continued his report. "The victims died of dehydration and blood loss, as suspected, complete extraction of all bodily fluids, even the bone marrow – but we couldn't determine the cause. There's no damage to the organs, no contusions, no puncture marks, nothing to indicate excessive heat or pressure. It's almost as if they were…well, freeze-dried."

"Freeze-dried?" Sarah shivered reflexively.

"All right there, old thing?" Harry promptly asked without thinking and then held up his hands in penitence, mea culpa, when she narrowed her eyes at him in silent protest at the nickname.

"That's what would have happened to me," she said with a shudder, distress visible in her ever-expressive face. "It's what started to happen to me, both times – I felt so cold, as if I were frozen to the spot – and there was something there, I know there was, pulling me out of myself."

"And that's what happened to Bartrum?" Landa shot a knowing glance at Utoblo's stricken expression.

"It's what happened to all of them," the Doctor sombrely confirmed.

"But how – why?"

He brightened. "I'm glad you asked, Samina. Tell me, what's your understanding of extra-dimensional cosmology?"

He made it sound rather as if this were something that everyone ought to be fully up to speed on. Landa blinked at him. "I'm a technician. I repair machines – I leave theology to the Lamas."

"Not theology, cosmology: the study of universes."

"Universes plural?" Harry was lost already – just the one universe, with everything in it, seemed more than enough to him.

"Yes, Harry: universes plural." The Doctor began to pace again, arms waving in expansive gestures to illustrate his point, eyes blazing with the thrill of scientific discovery. "Hundreds of universes – millions of universes – stacked up against one another…and over one another and under one another and alongside one another and through one another. Universes existing in dimensions we can't begin to comprehend, that can never meet and never cross…and yet sometimes, just sometimes, here and there, someone will stumble on a thin point: an impossible place where two incalculably unlike dimensions almost touch."

Stunned silence followed this impressive speech. Utoblo looked dumbfounded, Landa's eyes had gone wide and Ponti had reappeared at the entrance to the probe, gun in hand to bar their way but listening curiously.

Harry looked at Sarah, who seemed no more the wiser than he was.

"And that's where we are?" she asked. "At a thin point between universes?"

"Yes," said the Doctor with a decisive nod.

"You'll never convince the captain," Landa flatly declared, shaking her head.

"Ask not whether Captain Salamar believes in outer-dimensional beings," he loftily replied, adopting a sepulchral tone. "Ask rather, do those outer-dimensional beings believe in him?"

Harry tried to understand. "Let me get this straight. You're saying that this place is at the boundary between two universes and these deaths were caused by some kind of…creature from the other side?"

"In a nutshell," said the Doctor with a nod. "Yes."

Utoblo spoke up now, frowning. "But how does a creature from another universe kill people in this one? That doesn't make sense."

"A good question," said the Doctor, but before he could answer it, Captain Salamar appeared at the entrance to the probe, flanked by armed guards, a sheepish-looking Vishinsky at his shoulder, and a man Harry hadn't seen before at his heel, wild-eyed and haggard – the enigmatic Professor Sorenson, presumably. "Ah, Captain, about time, we need to talk," the Doctor began, an urgent bite to his determinedly jovial tone, but Salamar cut him off.

"Thank you, Doctor; your input is no longer required. Professor Sorenson has explained everything I need to know."

"He has? I doubt that. Captain, you must listen to me, we're all in the most terrible danger, for as long as we remain on this planet –"

"Then you will be delighted to hear that we are leaving," Salamar smartly interrupted. "Just as soon as we've loaded up the professor's cargo."

"What cargo?" As a note of trepidation entered the Doctor's voice, Harry exchanged uneasy glances with Sarah. The Doctor hadn't exactly explained his theory, but if he thought it worth worrying over, it was worth worrying over.

"That's classified information," Salamar snapped even as Sorenson pushed forward, calling out, "My samples, my research – rock formations on the very fringe of the universe, a new and inexhaustible source of energy –"

Salamar glared at the man, too late.

"Yes, I thought as much. A totally unknown mineral, something entirely new and undiscovered, a thing of beauty, and all you see is fuel, potential for profit – but you mustn't," the Doctor angrily protested. "Captain, you can't. Don't you realise? The deaths began when the survey team started their tests on the crystalline substance they'd discovered here, attempted to refine it –"

"Coincidence," Sorenson defensively claimed.

"Vengeance," the Doctor countered. "Something here doesn't want you to have those crystals. It will kill to protect them – already has."

"And who could have a better motive than a rival seeking to steal the Professor's work and claim credit themselves?" Salamar's pallid face flushed, his cold blue eyes flashing with moral indignation. "A rival such as you, Doctor. What other purpose could you possibly have here? Guards!"

Accused again – the turnaround was startlingly abrupt. As the guards surged forward, guns at the ready, Harry tried appealing to Vishinsky, who'd seemed so reasonable earlier and knew damn well that they hadn't killed anyone.

"Commander, you know we had nothing to do with those deaths, you've seen the evidence."

But the commander only shook his head. Shame and regret were written all over his face yet he refused to speak out against his captain's decision. "It's out of my hands, I'm sorry."

As the guards began to push and shove them back toward the base, the Doctor twisted free and lunged at Salamar, caught at his arm, still trying to convince him of the danger. "Salamar, you must listen –"

A flash from someone's gun and he collapsed where he stood.

"Doctor!" Sarah's cry of horror rang in Harry's ears as he instinctively surged forward, hardly even knowing what he was doing – the Doctor was down, injured, he had to check –

Another flash of light – and the world went dark.