'You want to go there?' said Bregman. 'Why, for G.o.d's sake?'

The Doctor leaned towards her, conspiratorially.

'I'm half-stupid,' he said. 'On my mother's side. If you feel up to the walk, it'd be nice to have some company.'

Up close, the castle/car park looked even worse than Bregman had expected. She guessed it'd take a good few hours to walk all the way around the base of it, so G.o.d knew how long it'd take to get to the top level. Through the opening at the front of the building, she could see the layout of the ground floor, a concrete hangar the size of a football field, marked with lines of white paint and splashes of dried blood. Bare yellow bulbs hung from the ceiling in their thousands, filling the building with a sick electric light, while the dead loitered in the shadows of the supporting columns, doing nothing in particular, the way only the dead really know how to do nothing in particular. The columns were stained with black graffiti, Bregman noticed, although you couldn't make out the letters. Presumably, there were no names in Mictlan.

The Doctor took it all in, but didn't seem fazed. Bregman wondered whether he was seeing a car park, too, or something worse. She felt it was fair to a.s.sume this was her her version of purgatory. She doubted it'd look the same to anyone else. version of purgatory. She doubted it'd look the same to anyone else.

A couple of minutes later, they found the way up to the next level, a fifteen-metre-wide stairwell set halfway along the ground-floor wall. The steps were huge, big enough to make Bregman think of a set from an old Hollywood musical. You could imagine the leading lady high-kicking her way down the stairs, belting out the theme song and trying not to break her stilettos on the solid concrete. The bulbs at the top of the stairway had blown, so everything faded into darkness after the first few dozen steps.

The Doctor started bounding up the stairs, two or three at a time. Bregman tried to keep up with him, but failed miserably. In the end, she had to shout at him to stop.

'I'm not well, all right?' she said, when she saw him glance back at her over his shoulder.

The Doctor looked agitated, but at least he'd stopped bouncing. 'I don't suppose there's any need to hurry. I was hoping to catch Trask before he handed the Relic over to the Celestis, but I think we're already too late for that. We're going to have to deal with the Celestis face-to-face.'

'"We"?'

The Doctor seemed taken aback. 'I'm sorry?'

Bregman stopped a couple of steps below him, and caught her breath. 'You wanted me to follow you here, OK? And so far, all I'm doing is slowing you down. Whatever you're doing, it's got nothing to do with me. I don't even know why you're here. So why drag me along? I mean, don't think I'm not enjoying the experience or anything.'

But the Doctor turned out to be entirely sarcasm-proof. 'It's got something to do with a tree falling in a forest,' he said, as if that explained everything. 'Oh, look. We've got company.'

Bregman looked up. At the top of the stairway (or, more accurately, at the point where the stairway vanished into the darkness), things were moving. Person-shaped things, shambling down the steps, muttering among themselves as they descended. Without thinking, Bregman took a step backwards, and almost lost her balance.

More of the dead. You could tell by the way they walked. But these moved with a purpose, and you could see, even through the shadows, that they had some traces of ident.i.ty left in them. The zombie elite, Bregman guessed. The chosen ones of Mictlan. One by one, the shapes staggered into the light, their eyes fixed on the Doctor.

The first of the dead men was black. He wore a brilliant red flower on his lapel, and there was a sharp white grin cut into his face, but it was a corpse's grin, the grin of someone who no longer had any need for a sense of humour.

Behind him, there were two figures dressed in dark designer suits, their faces pale, their hair cropped in a military style. Both wore sungla.s.ses, which hardly seemed appropriate here, and both had their hands tucked into their inside jacket pockets, fondling the handles of concealed firearms.

Two more humanoid figures stumbled into the light after them. Bregman thought of the slimy drug dealers you used to see in programmes like Miami Narcs Miami Narcs. The men had tanned skin and greasy hair. Their teeth were sharpened to points, and they wore gold medallions around their necks, although Mictlan had worn down the metal until it was almost as grey as the stairwell itself.

Next came a short, square-shouldered man, his hair slicked back and greying at the temples, his eyes points of black in a flabby white face. He looked like every G.o.dfather figure in every gangster movie ever made, and his head was almost lost in the enormous fur wrap he wore around his neck. The wrap was wriggling on his shoulders, needle-sharp teeth snapping at each end. A fashion accessory that wanted its own back.

The last two figures were both alien. The first was jet black in colour, covered in a carapace much like a beetle's, its arms ending in enormous lobster-like claws. Two steps above it stood a shape dressed in an ornate golden robe, a huge semicircular collar raised behind its head. Bregman got the feeling the robe was supposed to be a parody of a much more elegant style of clothing.

The eight figures, Mictlan's finest, marched down the steps in perfect time, until the nearest of them wasn't more than a metre or two from the Doctor. Then they stopped.

'The agents of the Celestis,' the Doctor mused. He didn't seem worried, and he hadn't backed away while the dead had been advancing. He glanced over his shoulder. 'It's all right, Kathleen. They're only puppets. Stand behind me, you'll be quite safe.'

Bregman hopped down a couple of steps anyway, but she didn't take her eyes off the dead. 'Safe how, exactly?'

'You're not really here, remember. Your mind is in Mictlan. Your body's safely back on Earth.'

'And what about you?'

The Doctor cleared his throat. 'I'm afraid I brought my body with me. I didn't really have a choice. Ah. Mr Trask.'

A ninth figure had appeared out of the darkness. Bregman almost choked. It was the thing... the person... the man man... she'd met in the ziggurat, just after she'd arrived in the Unthinkable City. The one who'd made her throw up.

And he was still smiling.

'Not true,' the creature told the Doctor.

'I beg your pardon?'

'Not true. Not safe. Her mind is here. So we can mark it. Make her one of ours.'

Bregman had no idea what this meant, though she saw the muscles tense up all over the Doctor's body, so she guessed it wasn't nice. 'You wouldn't dare,' he said.

'We could. We won't. Not the way we work. Never mark agents against their will. Never.' Trask indicated the figures around him with a stiff, mechanical wave. 'Us. All of us. We chose this. Chose to serve the Celestis.'

Bregman tried to focus on the man's face, but failed, the same way she'd failed the last time she'd seen him. Like most of the dead souls in Mictlan, he'd lost everything that had made him human, until his face was just a collection of lumps and holes, a shape without meaning.

As she watched, something else floated out of the shadows. It was the casket, Bregman realized. The moment it appeared, the Doctor's body went stiff as a board.

'The Relic,' Trask said. 'It's ours. Paid for it. Rules of the auction. We won.'

"Rules"? "Won"? The Doctor turned to Bregman again. 'You see how the Celestis think? Whatever happens in the real world, it's all a game to them. Without their bodies to hold them down, all they've got to worry about are their own little political feuds. They don't care who wins the war, as long as it makes life more interesting for them.'

'Yes,' said Trask. 'Games are important. Rules are important. Always obey the rules. Always honour agreements. Always keep deals. Cheating, otherwise. Like you cheat.'

The Doctor sniffed petulantly. 'I never cheat. Admittedly, I do sometimes make the game more complex, but I never cheat.'

'The Celestis had a deal. With you. You broke it.'

'Deal? What deal?'

Ancient muscles cracked and flexed inside Trask's face. 'The Celestis agreed. To let you conclude the battle on Dronid, in your own way. Without interference. In return, you promised. Promised your body. Now you want to steal it back. Cheating.'

'Not true,' the Doctor protested. 'I've never even met the Celestis, I've certainly never made any deals with them.'

'You will. One day.'

The Doctor looked alarmed. 'You're trying to hold me to a promise I haven't actually made yet?'

'Yes.'

'But that's not fair!'

'You promised. You made a deal. In your future.' And as one, the other figures on the stairway began to move again, those at the back of the formation turning to flank the Doctor. Trask kept croaking. 'We need your body. The Celestis need your body. To give you the mark. To make you ours. Our agent.'

Bregman hopped down another couple of steps, but the Doctor stayed where he was, his head held high. 'You can't have the Relic,' he reiterated, obviously doing his best to keep his voice steady.

'Don't want it. Don't want your body. Not the body in the coffin. Not any more. Something better.'

'I'm sorry?' said the Doctor.

'Dead body would make a good agent,' Trask went on. 'Not as good as your live body, though. No need for recorporation. Five regenerations left. Useful.'

All of a sudden, the Doctor seemed nervous. 'You can't have me, Trask. Not while I'm alive. You said so yourself. The Celestis' agents have to agree to be given the mark, of their own free will. It's the rules. And I don't agree.'

'Already have. You made a deal. You said we could have your body. You agreed. We never specified. Never said it had to be dead. Within the terms of the agreement. We never cheat.'

'You're going to try and give me the mark?' the Doctor spluttered. The dead had arranged themselves in a tight cl.u.s.ter around him, and the men in black had moved into position behind his back, to stop him retreating. As far as Bregman could tell, though, he didn't look like he was going to make a run for it. 'That doesn't make sense. If you thought you had the right to mark me at any time in my life, because of a promise I haven't even made yet, then why haven't you come for me before now?'

'We were waiting. For you to come to us. More powerful here. Here in Mictlan. Our territory. No way out.'

'I demand to see the Celestis personally!'

'No. Not yet. Not time. We can give you the mark ourselves. Make you one of us.'

'You can't '

'We can,' said Trask. 'Feel.'

And that was when, at long last, the Doctor tried to get away. He turned to run, but the alien with the black carapace snapped one of its claws shut across his shoulder, and the Hispanic thugs reached out to grab his arms. There was no point struggling, after that. Seconds later, every part of his body was being pinioned by the dead.

The living fur wrap barked excitedly. The black man's smile became a blur of brilliant white. The Doctor's eyes met Bregman's, and in that one moment, Bregman was sure she was ready to wake up and find herself back in the ziggurat.

Then his head jerked back. There was a tiny noise from the back of his throat. Bregman looked towards the top of the stairway, and saw Trask, standing motionless, his grin still in place, his eyes fixed on the Doctor. The mark, thought Bregman, that was what he'd said. The Doctor was being branded, turned into an agent of Mictlan. Trask was reaching into his skull, scratching something across the surface of his mind.

She didn't move. Couldn't move. She stood and watched until, eventually, it was all over.

The dead let go of the Doctor's limbs. His head lolled forward, and his arms dropped to his sides. The zombies moved away, leaving him to stand on his own two feet. He wobbled for a few moments, but he managed to stay upright. Finally, he opened his eyes.

The first thing he did was look at Bregman, and Bregman would have screamed, if she'd been alive enough to really care. There was something tearing and thrashing inside his head, you could see it in his irises, something trying to gouge out his memories and rip up his personality. There was no emotion on his face. No trace of feeling.

'Interesting,' he said.

He spun on his heel, to face Trask. The rest of the dead were stumbling away, being swallowed up by the darkness at the top of the stairs, but Trask didn't move.

'Concentrated Celestine consciousness,' the Doctor went on. 'Planted directly in the mind of the subject, without any need for surface psychic or psionic penetration.'

'Yes,' said Trask.

'Doctor?' Bregman said. She wanted to say something caring and considerate, like "how are you?", but she knew how stupid it'd sound. Besides, the Doctor was ignoring her.

'What should I do?' the Doctor asked Trask.

'Go back to Earth. Return to your TARDIS. You will be given orders. When we need you. The Celestis can contact you directly. Through the mark.'

'And the Relic?'

The casket was hovering at Trask's feet, anxiously bobbing up and down on its antigravs. 'Worthless,' Trask declared. 'Your timeline has changed. The Relic is a paradox. Too dangerous. Too dangerous to use. Could strengthen the Faction. Can't be allowed.'

'Shall I destroy it?' the Doctor asked.

Trask nodded, his head creaking on top of his rigor-mortis neck. The Doctor put two fingers in his mouth, and whistled. The casket obediently wobbled down to his level. It seemed glad to get out of Trask's presence.

Satisfied, Trask turned away, and began climbing the stairs. Seconds later, he disappeared into the darkness, along with the rest of Mictlan's elite.

The Doctor caught Bregman's eye again. There was a fraction of a smile on his lips.

'Wake up,' he said. And he snapped his fingers.

'Isn't there any way we can scan the City for him?' asked the human girl. Sam, Qixotl reminded himself.

'Treat me with a little kindness and understanding here, OK?' he said. 'I've already died once today. Y'know, a thing like that doesn't get you in a great mood. Anyway, the Doctor's going to be fine. Really. I mean, wherever he's got to.'

'Right,' Sam murmured.

Actually, Qixotl had a pretty good idea where the Doctor had got to. As soon as the Time Lord had found out about Trask, he'd stormed out of the conference hall, turned the corner... and vanished. Sam had searched the corridor, but there hadn't been any sign of him. Which kind of suggested the Doctor had gone to Mictlan after Trask, though Qixotl couldn't for the life of him figure out how.

And if that were true, then he probably wouldn't be coming back. By rights, Qixotl should have been on his ship and out of this solar system by now, but he had the horrible feeling that if he left the City without debriefing the other bidders, they'd be following him around until doomsday, demanding to know what he'd been trying to pull. So he was lounging around the conference hall with Sam, waiting for the others to show up, and wondering exactly how many of them had been killed by the Krotons.

'I could do with some help,' the Doctor said.

Qixotl yelped, and fell off his chair. The Doctor had reappeared in the archway, his face all twisted and crumpled, like he was sucking on the biggest citrus fruit in history. The UNISYC Lieutenant was leaning against him, looking dazed and wobbly. More importantly, the Relic was hovering in the pa.s.sageway behind the two of them, glowing cheerily.

Sam jumped to her feet, and hurried over to the Time Lord's side like a little puppy. She took the Lieutenant's arm, then led the woman towards the nearest available chair. The Doctor collapsed against the frame of the archway, looking exhausted.

'I see you, er, got the stiff back,' Qixotl ventured.

The Doctor stared at him.

The stare was horrible. Really, really nasty. Qixotl could see things in the Doctor's eyes, terrible churning things, trying to break free of his head.

'Don't trust him,' gurgled the Lieutenant.

'Don't trust who?' said Sam.

The woman raised her hand, and pointed an accusing finger at the Doctor. Her face was a deathly white, Qixotl saw, and her limbs were seriously shaking. 'He's one of them. One of the dead. He's got the mark. I saw it. I saw it happen.'

'Oh, h.e.l.l,' said Qixotl.

Sam gawped at the Doctor. 'Doctor...?'