'What about the Relic?' asked the Doctor's pet.

The Doctor looked pleased with her. He was probably training the girl, thought Qixotl. 'I hadn't forgotten, Sam. We can collect the Relic before we leave.'

'Who can collect it?' demanded Homunculette. can collect it?' demanded Homunculette.

The Doctor sighed. 'We can all do it together, if you like.'

'Just as long as the Krotons don't take it,' Sam added. Qixotl got the impression she'd only said it to make herself feel like she was part of the conversation. The Doctor gave her an encouraging smile.

'Yes. Although, to be precise, there is only the one Kroton here '

He froze in mid-sentence. The smile dropped off his face.

'Qixotl,' he said.

'Er, yeah?'

'Do you remember what E-Kobalt said, when he arrived?'

Qixotl blew through his lips. 'Don't ask me. I didn't understand most of it. Oh, yeah, I know. He said he'd intercepted that black s.p.a.ceship, but he'd already sent for... oh, h.e.l.l.'

'I knew we'd forgotten something,' the Doctor muttered.

And at that moment, with a sense of timing that could only have been called impeccable, there was an ominous rumbling from outside the ziggurat.

E-Kobalt ceased its reminiscing, and listened to what the control growth had to tell it.

Kilometres above the surface of the planet, the sky was unfolding, revealing things that had travelled here under the skin of s.p.a.ce-time, unseen by the universe-at-large. The ships were made of crystal, grown on the looms of Quartzel-88, their shapes unmistakable. As they came into contact with the Earth's atmosphere, their engines caused wild fluctuations in the planet's psychic aurora, as superspatial drives often did. E-Kobalt thought of the effects the disturbances might have on the bipeds here, and found the notion amusing. As much as anything could be found amusing by a Kroton.

The ships the dynatropes descended. They moved fast, faster than the vessel E-Kobalt had arrived in. Soon, they were within visual range. E-Kobalt watched them through the sensory apparatus of the control growth.

There were ten of the dynatropes, arranged in an upside-down tetrahedron, with the spearhead craft at the bottom of the formation and the six long-range artillery craft at the top. They were pale and jagged, like enormous pulled teeth, and they spun as they fell, filling the air with a deep, discordant warbling, loud enough to shake the walls of the City below.

Ten ships. A Warspear. The dynatropes unfolded their probe limbs, sweeping the atmosphere, searching for information. E-Kobalt let a little more of his consciousness seep into the control growth, then warbled back to the Warspear on the standard communications frequency.

It was ready to make its report. And, as the commander of this unit, it knew the others would listen to any ideas it might have about how to deal with the alien bipeds.

'A Kroton Warspear,' the Doctor explained.

Sam bounded along by his side, inquisitive as ever. She'd all but forgotten what had happened the last time she'd gone down to the vault, the Doctor realised. One whiff of action, and she was her old self again. The perfect companion.

The perfect companion...

They were hurrying down the steps now, Qixotl, Kortez, Homunculette, and the two Paradox cultists in tow. n.o.body trusted anybody else to take care of the Relic, so they were all heading for the lowest level together. Homunculette and Manjuele never took their eyes off each other, while Kortez spent most of the time staring at the broken skin on his hands and humming something that sounded slightly Tibetan. Of all the surviving bidders, only Trask was absent. The dead man had vanished at some point; n.o.body had spotted where or when, exactly, but the Doctor doubted it mattered. Even if he was faster than the average corpse, he was hardly likely to get to the vault before them and make off with the Relic.

The Doctor tutted to himself. Once they reached the Faction's shrine, they'd be safe from the Krotons, but he had no idea what would happen then. He imagined the bidders sharing out the Relic between themselves. An arm for the Celestis, a leg for Homunculette, a pancreas for the Faction...

'What's a Warspear?' Sam queried.

The Doctor stopped pontificating. 'I'm not sure. I've met the Krotons before, but only isolated units. I think it's safe to a.s.sume the reinforcements are going to be heavily armed, though.'

'What about Kathleen?' Sam asked.

'And what about Marie?' wheezed Homunculette.

The Doctor waved the questions aside. 'We'll pick them up as we go. But we're running out of time. Keep moving.'

The Relic is the important thing.

The Doctor nodded. 'Exactly. The Relic is the important thing.'

The Relic has a message.

'The Relic has a message,' the Doctor repeated.

'Sorry, what?' said Sam.

'I said, the Relic '

The Doctor stopped. Stopped dead. Stopped dead? Stupid expression to think of, at a time like this.

The Relic has a message, and it's very important.

The Doctor shook his fist in front of his face. 'Stop it,' he insisted.

'Stop what?' asked Sam.

'Not you.'

The Relic is...

'I said, stop it!' He closed his eyes, and started walking again, letting his feet find the steps on their own. He felt himself cross the landing on the first floor down, then move down the staircase towards the lowest level, brushing aside the remains of the retinal webs on the way.

Sam's voice drifted back into his consciousness. 'Doctor? You're picking up telepathic stuff again, aren't you?'

'Yes. Yes, I am.' The Doctor slipped, almost fell down the steps, but he recovered himself in the nick of time. Behind him, the bidders started muttering anxiously. 'Sam, please. Don't talk to me. It's hard keeping the voice out of my head. The closer I get to the casket...'

The closer you get to the casket, the closer you get to the future. I don't know why you're so afraid of your own body, Doctor. Think of it as a point of certainty in your life. A cornerstone. Everything else is so vague, these days. So changeable...

'I don't know what you're talking about.'

I think you do. You used to be so careful, as well. You always did your best to stop anything happening to the timeline. Remember when Adric drove that freighter full of antimatter into the Earth, and wiped out the dinosaurs for you? You felt like you'd lost so much, but let's be honest, you won that day. You did what you always do. You looked after history. You made sure the dinosaurs died out, dead on schedule.

'That's not true!'

I know, you've made a few small... let's not call them changes, let's call them improvisations. You've made sure a few people survived who wouldn't have survived. You've saved the odd human colony here, the occasional endangered species there. But wherever you went, you always made sure time ran its course. Until now, that is. Until this regeneration. You're not even thinking about the consequences anymore.

'Meaning?'

Just after you regenerated, remember? You went back and visited all your past lives. Changed your own timeline by doing it, too.

'It wasn't exactly my doing,' the Doctor protested.

You're blaming Ra.s.silion?

'Well... if you like.'

Isn't that a bit like a Christian blaming G.o.d for all his mistakes? Let me try another approach, maybe you'll see what I'm getting at. Sam thinks of you as a function of the universe. Really, that's the way she sees you. Not a person, exactly, more a kind of built-in feature of existence.

'That's not true,' said the Doctor. Actually, he had no idea whether it was true or not.

Let me finish. Think back to that time when you went to see your previous selves. What was the first thing you did, once you'd finished playing with your timeline? What was the first thing that happened, once you were sure you'd got your ident.i.ty back? I'll tell you, if you can't remember. You met up with Sam and took her on board the TARDIS. Almost as if some part of you knew what she represented, and had to complete the process.

'I don't understand. What does Sam represent?'

'Who, me?' said Sam.

'Shhh. I asked you a question.'

You know what Sam represents. If a tree falls in a forest and no one's there to hear it, does it make a sound? Stop me if I'm getting too abstract here, but if a Time Lord saves the world and n.o.body witnesses him doing it, does history care? She's your witness. The thing you need to make you whole. Your heart's desire. Maybe that's why she was created in the first place. You and she were made for each other, she said so herself. Smith and Jones. It's so obvious, it's almost painful.

'No!' The Doctor felt a hand on his arm, probably Sam's, but he shook it off. 'I'm not listening to you. You're the Shift. You're putting all these ideas in my head to distract me...'

If you believed that, we wouldn't be having this conversation. Well, all right. Perhaps I'm partly the Shift. There have been so many alien ideas bouncing around your head, I'm not surprised you're hearing voices. Your synapses are in a mess, believe me. Think of me as a kind of temporary psychosis.

'A psychosis? You mean, I'm talking to my own dementia?'

Don't worry. I'm sure it'll pa.s.s.

'THIS-IS-E-KO-BALT-PRIME-OF-THE-KRO-TON-FIFTH-LATT-ICE. WE-ARE-NOW-IN-CONTROL-OF-THIS-CI-TY.'

The Doctor opened his eyes. He was standing at the entrance to the vault, with the casket glowing smugly to itself on the other side of the dead kidney-garden. Around him, the others were clutching their ears. The Kroton's voice had echoed through the walls of the ziggurat, the same way the toucan alarms had. The Doctor guessed the City had been built to conduct sound that way. E-Kobalt was probably using some kind of PA system outside the building.

'YOU-WILL-SURREND-ER-THE-REL-IC-TO-US,' E-Kobalt went on. 'IF-YOU-O-BEY-YOU-WILL-BE-ALL-OWED-TO-LEAVE-THE-CI-TY-UN-HARMED. IF-YOU-RE-SIST-YOU-WILL-BE-DIS-PERSED.'

The Doctor felt his ears start to bleed. The voice was actually making the walls tremble, but at least it had blotted out the other voice, and for that he was grateful. He looked up at the ceiling. 'Listen to me, E-Kobalt. I don't know if you can hear me, but if you can, then listen. We can't let you have the Relic. We'll die before we surrender it. Do you understand?'

'Er, what did you say?' said Qixotl. He was crawling around on his knees, his hands still poised over his ears.

'I said, we'll die before we surrender the Relic.'

'Uh. I thought that's what you said.'

'Don't worry, it's only a figure of speech.'

'You think the Krotons know that?'

'KRO-TON-UN-ITS-HAVE-AL-READ-Y-BEEN-DIS-PATCHED,' intoned E-Kobalt. Thankfully, it said nothing else after that. The Doctor wondered if the Shift knew enough about the ziggurat to think of using the PA system as a sonic weapon, but he quickly put the thought out of his mind. Just in case the Shift found it there.

Homunculette pushed himself between the Doctor and the vault. 'That's got to be the Relic. How are we going to shift it?'

Qixotl got back on his feet. 'Not a problem. There are antigravs strapped to the bottom of the box, and there's a navicom in the lid. Sound-activated.'

'Really?' said the Doctor. He put two fingers in his mouth, and whistled.

'It only responds to me...' Qixotl began. But he didn't bother finishing the sentence. Slowly, very slowly, the casket lifted itself off the ground, and drifted across the vault towards them. The Doctor remembered the Hand of Omega, and all the happy hours he'd spent taking it for walks when he'd first made a home for himself on Earth.

The Relic floated right up to him, then lowered itself onto the ground. The other bidders took a step backwards.

'Good boy,' the Doctor said, patting the casket on the lid. He hoped n.o.body could tell how much he was squirming.

At the bottom of the artron by-product waste-shaft, the puddle was still remembering.

Specifically, it was remembering its first attempt at mating. Once the mating process had been completed, it had felt something detonate in its bigger-than-planets womb, a burst of life, a second micro-universe forming within the micro-universe of Marie's body. A second TARDIS. Near-infinity inside near-infinity.

The puddle remembered the sense of combined hatred, rage, and disappointment when the Time Lords had taken the infant TARDIS away, extracting it from the womb before it had even grown its first power cell. They'd put it into suspension, trapping it inside one of their little pan-dimensional boxes. It was only a child, they'd said. It needed proper supervision.

She'd never seen the infant again.

Another break in the memories.

Then Marie was in the ziggurat, her weapons systems bringing themselves on-line. She told them to stop, but they refused to listen. She felt the sh.e.l.l of her body opening up. New impulses, new responses.

She knew who Trask was working for. She knew who the Shift was working for. In some part of her cognitive core, she even understood what the Shift was planning, and guessed what it would try to do if it failed.

The memory acid had been dispersed. Marie's past was lying in pools around the interior of her body, each part remembering something, no part remembering everything. The puddle congealed, becoming a semi-solid, then threw out feelers, tiny shoots of grey ooze that probed the bottom of the shaft. The memory acid had been designed to be adaptive, self-repairing, and self-reliant. The puddle knew it had to find the rest of Marie's ident.i.ty. It knew it had to put her back together again.

One of the feelers attached itself to the side of the shaft, and dragged the rest of the puddle's ma.s.s after it. Slowly, very slowly, the puddle began to climb.

Homunculette's guest room looked like a military barracks. Cousin Justine experienced a brief twinge of satisfaction when she saw it. A few centuries ago, a Time Lord's guest room would have been a monument to opulence, all Ionic columns and gold tr.i.m.m.i.n.gs. But here, the fittings were grey and functional, and the air on the other side of the doorway stank of male hormones instead of incense. This is what half a millennium of warfare can do to a race, Justine decided. And n.o.body deserved it more than the Time Lords.

From the corridor, she watched Homunculette bending over his TARDIS, staring into the machine's eyes as if she were a sick kitten. 'She's getting better,' Homunculette grumbled. 'I can see the memory patterns coming together in the iris monitors.'