'I-den-ti-fy-yourself,' burbled a voice from around the corner. Sam winced.

'I am the Doctor,' the Doctor declared. He made it sound like an important announcement, like he was reading out the nominations for an academy award. 'I think your commander wants to speak to me. Perhaps you'd better tell him... tell it it... where I am.'

There was a pause. Sam guessed the thing would be swivelling its head at him in a menacing fashion. 'You-are-a-known-en-em-y-of-the-Kro-ton-Ab-so-lute. The-First-Lattice-has-gi-ven-orders-that-your-bo-dy-is-to-be-re-covered-at-all-costs.'

The Doctor spread his arms wide. 'Well, here it is. That is, if you believe I really am the Doctor.'

'Explain.'

The Doctor gave Sam a quick sideways glance. 'Just a pa.s.sing thought. I could be anybody, for all you know. Some poor deluded pa.s.ser-by, desperate for attention.'

Then something dramatic happened. A crystal spike, presumably part of the Kroton, lashed out at the Doctor. Sam jumped. The spike had shot down the pa.s.sage like a bullet from a gun, but the Doctor had side-stepped it almost without seeming to notice. It had flown right past him, and embedded itself in the wall.

It was a tendril, Sam saw. Flexible, but sharpened to a point. The tendril had splintered when it had hit the wall, leaving small flecks of crystal littering the floor around the Doctor, and now the extension was twitching, trying to pull itself free of the stone. There was a low groaning noise, which Sam interpreted as a Kroton wail of anguish.

The Doctor reached down, swept up the largest available piece of shattered crystal, and hot-footed it back down the pa.s.sage towards her.

'What...?' Sam said, knowing full well she'd never get the chance to finish the sentence.

'Bioma.s.s intake tube,' the Doctor rattled. 'It was trying to take a sample from me. Come on. Into the shrine.'

'You-will-not-move!' gargled the Kroton, around the corner.

'Why...?' Sam began.

He waved the shard of broken crystal in front of her face. 'Kroton bioma.s.s. We're holding our own ritual, and everybody's invited. I said, into the shrine. Quickly!'

Mr Qixotl wasn't dead. This surprised him as much as it would have surprised anyone.

It's not as if I planned for this or anything, he said to himself, as he lay on the floor with his guts hanging out. It's not as if I had some secret surprise force-field generator hidden under my vest, just in case. I'm lying here with a hole in my chest you could use as a punchbowl, and my legs all squashed where the Krotons rolled over them, and I haven't a clue why I'm still breathing.

Then he noticed that, as it happened, he wasn't breathing.

d.a.m.n.

Obviously, he was going through one of those strange time-slowing-down experiences people had when they were on the brink of snuffing it. Qixotl lay back, closed his eyes, and let himself go with it. There was no point agonising. The easiest thing to do was get some rest and wait for death.

But death only sent a representative.

'Qixotl,' said Trask. Mr Qixotl stared up at the walking corpse, and even now, even in his dying moments, he felt himself squirm. A nasty thought suddenly struck him.

'Oh no,' he said. 'I'm one of you, aren't I? I'm one of the living dead.'

Trask tried to shake his head, but the muscles must have been too stiff, because he gave up after a second or two. 'No. Qixotl. Not dead. Mortal stasis.'

'Sorry?'

'Mortal stasis. My employers. The Celestis. They can hold off your moment of death. For a while. Not long. Long enough for us to talk. To finish the deal.'

Then Qixotl remembered. The deal, the one Trask had offered him back in the guest room. At the time, the offer had sounded like a bad head-trip, but all of a sudden it seem to make perfect sense. 'You mean... now? You can actually...?'

'Yes.'

Qixotl tried to laugh, but his diaphragm didn't feel up to the task, what with the gaping wound in his torso and all. 'OK, Mr Trask. You've got my attention. Let's talk. Just make sure I don't snuff it halfway through a sentence, yeah?'

The Doctor tried to forget everything that wasn't important. The horrible decor of the shrine, the nasty itching sensation in his temples which he a.s.sumed was an allergic reaction to Paradox technology, the sound of the Kroton slowly rumbling down the pa.s.sage outside... well, all right, the Kroton slowly rumbling down the pa.s.sage outside was pushing the boundaries of "not important", but he had to concentrate.

There'd been a biosampler lying on the floor next to the control dais. It was a disgusting piece of apparatus, the same kind of voodoo science he'd seen on Dronid, but he'd been glad to see it there all the same. It meant he wouldn't have to use a penknife. The thought had been bothering him ever since he'd come up with the plan.

'Doctor? You're not going to do what I think you're going to do, are you?'

The Doctor slipped the biosampler over his fingers, and felt the metal rings close around his knuckles. 'If I know you well enough to think I know what you'll be thinking I'm thinking about, Sam, then... actually, I don't know. You're distracting me. Stop it.'

'Sorry.'

The Doctor took one last look around the shrine. The technology was no more complex than that of the TARDIS, but the operating system was different. He had to perform the ritual as if it were a holy duty. It was the only way of getting the shrine to understand him.

He dropped the shard of Kroton crystal onto the dais. There was a pause, and for a moment he thought the plan wasn't even going to get past stage one, but then the shrine started humming in his ear. It wasn't used to crystalline bioma.s.s, the Doctor concluded.

'I'd like to say a few words on this solemn occasion,' he intoned. 'Rabbits rabbits rabbits. Let sleeping dogs lie. There's many a slip 'twixt a cup and a lap. Boiled beef and carrots.'

'What?' said Sam.

The Doctor shushed her. If it sounded like a ritual, he reasoned, it'd probably be enough for the shrine. He pulled back the sleeve of his jacket, and pressed the spines of the biomsampler against the skin. Sam looked suitably appalled.

Was this the right thing to do? Yes, it might be the only way to stop the Krotons destroying the Unthinkable City, but could he, in all conscience, feed his own biodata to the shrine? After all, wasn't the whole point of the exercise to stop his biodata falling into the wrong hands?

No no no. There was no choice. He was trying to find an excuse not to go through with the rite, that was all.

He drove the spines into the flesh of his forearm. There was a hissing, popping sound, as his biodata was encoded into the buffer fluid inside the collection valves. The biosampler would only be making a surface scan, the Doctor knew, but it'd be enough to complete the rite. And hopefully, not enough to be useful to the Faction, after all this was over.

The skulls hummed a little louder, anxious to be fed. Their moaning melded with the rumbling outside, as the Kroton rolled along the corridor towards the shrine. The Doctor held out the hand with the biosampler attached, and flexed the muscles in his fingers. The fluid plopped onto the dais.

The Spirits came.

The Doctor felt the air freezing up in his lungs. He hadn't expected it to happen this quickly. Maybe it was him. Maybe the Spirits knew he was a Time Lord, and knew he had no place here. They were circling him, surrounding him, their invisible bodies spilling from the dead mouths of the skulls, the babble of all s.p.a.ce and Time dripping from their tongues. He turned his head, but his muscles were slow to respond. When he finally managed to focus on Sam, she was frozen, her mouth locked open, her eyes caught in mid-blink.

Time was slowing, just for him. The Spirits were squeezing themselves into the cracks between one moment and the next, building themselves a tiny continuum there, a split-second universe that only he and they could inhabit. This was absurd, the Doctor reminded himself, of course it was absurd. There were no Spirits, everybody knew that. There were just the forces of s.p.a.ce and Time, uncaring and impersonal; only Faction Paradox would be mad enough to turn them into G.o.ds. But here, in the shrine the Faction had built, it was impossible to think of them any other way. Yes, legend claimed there had been a Grandfather Paradox, once, but if so, then why was there no record of his existence in the High Council's files? It was all rumour, rumour and myth, it wasn't real, it couldn't be real...

Time slowed, and slowed, and slowed, until the Doctor wondered if the entire fourth dimension was going to collapse into a single point. He'd thought, like the idiot he was, that if he activated the shrine's engines, he'd be able to communicate with its control systems. But the shrine was big, bigger than he'd expected, almost as powerful as one of the TARDIS units it had been modelled on. His mind wasn't strong enough to control it, not without the techniques of the Faction to help him. He wondered if he'd be here forever, frozen in this one moment of existence, never being able to break free of the shrine's grip.

Then this was it. The end. Or rather, an eternity of never having an end. No escape, no last-minute rescue.

Defeatist thinking.

But logical.

When have I ever been logical? And why am I arguing with myself, anyway?

You're arguing with yourself because you don't have anybody else to argue with. Except for the Spirits, but the Spirits don't care.

Oh no. You again. I thought you said you were a "temporary" psychosis?

I am. All this exposure to Paradox technology must have triggered a relapse. Don't worry about it, I'll be gone soon enough. Once you're used to the idea of spending the rest of your life here, anyway. Sorry, what were we talking about before?

I don't want to talk to you. Talking to one's madnesses is the first sign of madness.

Oh yes. We were talking about Sam. We were saying how convenient it was, that a girl like her should turn up just when you needed her most. And she does have two sets of biodata. You've guessed that, haven't you? Qixotl didn't notice it, but only because the two sets are so similar, from a non-human's point of view. Something's altered her timeline, Doctor. Something's filtered out her self-destructive impulses. Turned her into TARDIS fodder.

Don't be ridiculous. Who'd do a thing like... oh. Oh, I see.

What do you see?

You're saying Sam's a plant. An agent for another power, is that it?

Hmm. Not that I want to insult the girl, but I don't think Sam's quite cut out to be a Wolf of Fenric. Do you?

Ra.s.silon!

I'm sorry?

Ra.s.silon. He was the last major life force I met before Sam arrived on the TARDIS. If she's part of his game...

Oh, good grief. You have to blame him for everything, don't you? n.o.body "planted" Sam. You've seen the truth, here in the ziggurat. You've seen the effect you can have on the universe. You've seen the damage you can do, without even lifting a finger. Without even having to be alive, come to think of it.

What are you suggesting?

Remember what I told you? About you being a living equation, a function of the universe. Well, suppose the function thinks it's incomplete. What happens then? Suppose, on some deep-rooted unconscious level, you feel like you need someone to be there for you. The function reaches out into the vortex... which is quite easy, let's be honest, because your biodata's wired into the vortex anyway... and finds someone. Someone it can make part of itself. A few little alterations to the timeline, that's all it takes.

I don't believe it. It's not possible.

You've got things in your biodata no one else has got, remember? Or you will have, at some point before you die. Things powerful enough to let your subconscious bend the timelines all by itself. That's why your bioma.s.s is so valuable, I'd guess. And that's the worst part, isn't it? You must affect everyone like that, one way or another. It's like I said. You never think of the consequences.

No. I still don't believe it.

Sam has two sets of biodata...

You're obsessed! There are things that can cause that kind of anomaly. You know that. Wrinkles in the continuum. Being on board the TARDIS would make her p.r.o.ne to that kind of distortion anyway.

Possibly. Possibly not. But what happens if you ever find out it's all your doing? The idea's been bothering you ever since the vault, I know it has.

No. If that were true, then... no. I won't listen.

'Doctor?'

Say what you like. I know you're wrong.

'Doctor, can you hear me?'

It's no good, I'm not going to... hold on a minute. Your voice has changed.

'Doctor, please try to listen.' It wasn't the psychosis speaking, the Doctor realised. He became aware of something else inside his split-second universe, another intelligence squeezing itself into the cracks. The Spirits howled and gnashed their teeth, obviously considering the intrusion to be rude.

'Marie,' thought the Doctor, knowing she'd be able to hear the thought.

Marie flexed the muscles of her pan-dimensional body, in a gesture the Doctor took to be a nod. 'I know who you are, Doctor. I had a long time to consider the situation. Or at least, parts of me did. It wasn't easy, working it all out. Not with my mind in that many pieces.'

'Homunculette said you were out of action.'

'A lot of my systems are still off-line. My memory isn't complete yet. But I can move. I know what you're doing, incidentally. Your plan to get rid of the Krotons. It's novel, I'll give you that much.'

The Doctor gave her the telepathic equivalent of a smile. 'I thought I could control the shrine. I was wrong. Can you complete the plan for me? If you materialise '

'No. My structure isn't stable enough.' Marie hesitated for a moment. 'But I can help you. I can connect my telepathic circuits to those of the shrine. The technology's compatible, I think. I can get the shrine under control for you. You should be able to pilot it from where you are. Incidentally, did you know there's a smudge on your psychic template? It seems to be some kind of psychological dysfunction.'

'So it told me,' the Doctor said. 'Don't worry, it's only a bit of random angst. It'll sort itself out once this is over. If you'd be so kind as to engage the telepathic circuits...?'

'Consider it done,' said Marie.

Then the Spirits began to wail. Not their usual mindless screeching, the Doctor noted, but a cry of sheer frustration. They could feel the intruder in the systems, keeping them in check, bending the shrine to her will. Within moments, Marie had finished the job. The racket died down. The split-second universe cracked open, letting in pure molten time, first as a trickle, then as a deluge.

Things started to move in the universe outside. Sam's mouth was closing. More worryingly, the Kroton was rolling through the doorway, its intake tube drooping from a split at the front of its body.

The Doctor stretched his nervous system, reaching out for the inner circuitry of the shrine. With all the energy his consciousness could muster, he ordered it to dematerialise.

Through the senses of the control growth, E-Kobalt watched the dynatropes move into firing positions around the City. The vessels were equipped with hyperbolic resonators, capable of cycling through every conceivable frequency in under a second, shaking apart anything from humanoid flesh to reinforced durilinium. More effective than simple dispersion weapons, E-Kobalt decided. Naturally, the devices had been grown on the looms of Quartzel-88, like so many of the Kroton Absolute's greatest creations.

And to think, pondered E-Kobalt, that I offered the Qixotl unit weapons like these in exchange for the Relic. A folly. It was so simple to capture the Relic by force.

The thought made it uneasy, for some reason. E-Kobalt tried to pin the feeling down, but it kept slipping through the links of its cranial unit. The grand notion was still throbbing away in its brain; kill the bipeds, smash the City. But then there was that other idea, smaller, yet just as intense, keeping a check on its aggressive instincts. Get the Relic first. Whatever you do, get the Relic first.

E-Kobalt wasn't used to thinking this way. Its brain wasn't exactly subtle, but it was at least capable of weighing up multiple options. Never before had it thought anything with so much clarity. Destroy, but wait. Destroy, but wait.

The sky turned black. It happened without warning, and it happened in a second.

In their dynatropes, the Warspear pilots panicked. E-Kobalt felt their vibrations on the fringes of its own mind, and for the first few seconds of the crisis its head spun out of control, trying to take in every detail at once. The control growth reported that the black ship, and indeed the whole Warspear, was no longer where it had been. The City had disappeared. So had all traces of the Earth. Instead, the Warspear was surrounded by walls.