'The natural order. The laws of balance all flesh must obey. All things are ordained, even this.' The Colonel slid the backpack off his shoulders as he moved, and by the time he reached the bottom of the stairway his hand was already rummaging through the contents. 'I have something. Something to aid the cause in the struggle to come. A token of our destiny.'

The Doctor looked between the stairway and the Colonel, as if trying to work out whether this conversation could possibly be more important than chasing the alien. 'Will it help me move faster, at all?'

Kortez finished rummaging, then held out his hand. Sam peered at the object sitting in his palm. It was a circle of metal, the same shape as a discus, and about the same size. The thing was Saab-black and Saab-smooth, but marked with a series of fuzzy pink pictograms around the rim. The symbols flashed and changed as Sam watched, though they didn't seem electronic. They looked more like they'd been painted on.

The Doctor seemed alarmed. 'A bomb?'

'Yes. Saskatoon. You remember, Doctor. It was a good day. We made sure the will of the eternal consciousness was done.'

'A thermosystron bomb,' breathed the Doctor. 'I thought I made sure they were all destroyed.'

Kortez nodded. 'They were. Except for this.'

'You didn't report it to the General?'

'Destiny. I knew that somehow, some day, this device would have a greater part to play in the web of karmic fate. Today is that day. We must stop the enemy. It's the will of the one true mind of all things.'

Sam coughed nervously. 'Er, Doctor...?'

The Doctor swept up the bomb, then slipped it into his pocket. 'Thank you, Colonel. Now, if you'll excuse me?'

He darted up the steps. Sam watched the Colonel turn away before she followed. The man looked content. Satisfied. Like he thought he'd done his duty, and done it well.

Sam drew level with the Doctor halfway up the first flight of stairs. 'He's mad, isn't he?' she asked.

'He's a little upset,' the Doctor admitted. 'Saskatoon was a very difficult affair.'

'You mean, he's mad.'

'Well, in a manner of speaking.'

'And that stuff about destiny?'

'His imagination's getting the better of him. There's no room for destiny in a universe this small.' The slightest of frowns appeared on the Doctor's face. 'With one or two notable exceptions.'

They reached a small landing on the first floor up. Various gloomy archways led to various gloomy corridors, and there was a stairway up to the next level off to one side. 'What about the bomb?' Sam queried. 'I thought you didn't like using weapons. Especially not those those sorts of weapons.' sorts of weapons.'

'I don't. But if somebody's going to be walking around with a piece of Selachian maximum impact implosive in his pocket, I'd rather it was me than the Colonel. Oh.'

The Doctor froze. Sam froze, too.

They were at the bottom of the next stairway by now. Standing at the top of the flight, on the second-floor landing, was the alien Sam had seen waddling past the guest room. It had turned to face them, and now it was covering the lower landing with one of its wobbly limbs. The arm ended in a thick tube, Sam saw, open at the end. It reminded her of a bazooka. Big, chunky, lethal-looking.

The Doctor grabbed the sleeve of her t-shirt. It tore as he tugged it, but the tug was enough to make her stumble back towards the top of the last stairway. They ducked through the archway, as the landing in front of them was filled with a dense white smoke. Sam squinted into the haze. No, it wasn't smoke. It was a cloud full of crystals. Tiny, razor-edged crystals.

The cloud began to settle. She heard the sound of heavy footsteps, climbing the stairs above them. Sam moved forward, to re-enter the landing.

The Doctor pulled her back again. Shaking his head, he reached into his jacket, and pulled out what seemed to be the first thing that came to hand. It was a fairy-cake, covered in fluff. The Doctor looked puzzled, clearly having no idea where the item had come from.

He lobbed the cake onto the landing. As it flipped through the air, small holes opened up in its surface, as if hundreds of tiny invisible mouths were trying to get at the currants. By the time it hit the ground, the cake was nothing more than a collection of crumbs.

'Each of the crystals is a miniature corrosive device,' the Doctor mumbled. 'A cloud of them is enough to gnaw an organic life-form to the bone in seconds. They disperse the waste material as dust. The corrosive's more powerful than I expected, though. Even after the cloud settles, the atmosphere's still deadly. Now we know what happened to the ship's pilot.' He nodded towards the walls of the landing. The stone there was covered in a thin sheen of crystal. Parts of the wall were starting to drip like melted wax.

'So, how do we get past?'

'We don't. The stairway's going to be a deathtrap for a good while yet.' The Doctor looked up at the ceiling. Sam got the impression he was trying to stare through the stone and watch what was happening on the roof. 'Let's hope the Shift decides to leave now. If it really is determined to complete its mission, things could get very nasty indeed.'

Sam, of course, didn't understand a word of this.

E-Kobalt-Prime extended its pincer attachment, then eased it into the control growth, which by now had firmly taken root inside the black ship's systems. At the Kroton's touch, the hatchway sealed itself shut, and the floor began to ripple, very gently, as the vessel's engines were brought on-line.

E-Kobalt could not, in all honesty, have been called unhappy. The auction hadn't gone well, but that hardly seemed important now. It no longer saw any reason to communicate with the other bidders. It had always believed carbon-based life to be unreliable, and events in the ziggurat had proved that all its worst ideas about alien animals had been correct.

Diplomacy had failed, but the City's defences were down. E-Kobalt had discovered this on the stairs, when it had tested its weapons attachment and filled the air with corrosive. The humanoids wouldn't be able to pursue it now. They would be destroyed, cleanly and efficiently, and the Relic would become the property of the Kroton Absolute.

That one single idea, that simple devotion to the most basic of military instincts, was now the linchpin of E-Kobalt's entire psyche. It issued another order to the control growth. The engines throbbed, and the black ship began to lift itself off the roof of the ziggurat.

Meanwhile, in the darkest depths of the Kroton's subconscious, the Shift allowed itself the conceptual equivalent of a satisfied nod.

THE SHIFT'S STORY

Darkness, no easily discernible time

They were taking him apart. The thought should have scared him more than it did, but then, it wasn't the worst thing that had happened to him today. He could still remember how it felt to lie under a Day-Glo yellow sun, with snow blowing into the cracks in his body. He could even remember knowing he was about to die. A gentle, creeping feeling. Not a single moment of horror, not the way he would have imagined it.

They were taking him apart. Soon, there wouldn't be anything left of him, not anything you could touch. Almost idly, he noticed that he didn't have a brain left. He didn't know how he could think without a brain, but he seemed to be getting by.

Before, he'd been a person, one insignificant little element of the Gabrielidean Nth Platoon. Now, he was even less than that. Just the idea of a person. A set of memories with no one to remember them. A thought without a head.

He concentrated on the memories. He let himself remember his final hour of life in the material universe.

Darkness.

He was cold. He would have been in pain, if all his senses had been working, but he was lying with his back against the ice, and the temperature had short-circuited most of the nerves across his torso. The nerves of his human suit, anyway. His real body sloshed around inside the skin, doing its best to keep itself warm. His brain was still hooked into the suit's nervous system, so he was feeling the cold the way a human would have felt it. Looking at the world through human eyes.

He couldn't see much, though. Whiteness from here to the edge of the world. A landscape made from six-hundred kinds of snow, shining in the sunlight, but never getting round to thawing. There was no night, he'd been told, not here. Something to do with some aurora or other. The sky was lit by stripes of orange and turquoise, brilliant psychedelic arcs that reached from horizon to horizon. The first scouting mission that had been sent here had gone mad. When the Nth Platoon had been a.s.signed to the planet, the troops had wired neural suppressors into the eyes of their human suits, to blot out the psychological side-effects of the light.

He tried moving his head. His neck didn't seem to want to turn, but he managed to force it.

That was when he saw the rest of his body, sprawled out in front of him, the snow already starting to bury his limbs. He wanted to close his eyes, but his eyelids didn't respond to the command. The torso of the human suit had split open, revealing the churning ma.s.s of his true body inside. One entire arm had come loose, and his bioma.s.s was spilling out of the sleeve in slicks of brilliant pink. One of the suit's legs had been torn off, as well, but he couldn't see whether he was leaking out of the wound there.

Every part of the suit had been armoured. Every flake of skin had been sprayed with bulletproof plasticrene. It hadn't made one bit of difference. The sergeant had sent him out on a recon sweep, and the combat satellite had located him while he'd been away from the rest of the platoon. It had fired on him, once, from somewhere in the upper atmosphere, then it had left him alone. Perhaps it had thought he wasn't likely to be much of a threat, with his spinal column shattered, his skin broken open, and the body inside slowly freezing.

A cl.u.s.ter of silhouettes appeared on the horizon in front of him, tiny smears of black against the blazing white background. He guessed, he hoped, it was the rest of the Nth Platoon, the sergeant and all her little boot-lickers. He thought of calling out to them, but he guessed there wasn't much point.

Then everything started to fade to black. His eyelids were closing, he realised. The software controlling his face had finally figured out that his eyes needed rest, occasionally.

He wondered if he'd be able to wake up again.

Darkness.

'...have to leave him here. OK. Get your palm-scans tuned, this is going to be the hard part.'

He was conscious again, but he didn't have the strength to open his eyes. Besides, he knew what he'd see. The sergeant, in her head-and-shoulders-above-the-rest human suit, coated in spray-on armour from top to toe. The troops had found him, and it sounded like they weren't thinking of taking him with them.

Military procedure. Of course. There hadn't been s.p.a.ce for a doctor inside the transit capsule, so the wounded could go and die on their own time, as far as the sergeant was concerned. He could hear the sounds of boots, scrunching against the ice. The other members of the platoon, obviously, getting tooled up for the big a.s.sault. They'd be checking their palm-scans, giving the terrain the once-over. They'd be looking nervous, too. Sweating deep red inside their suits.

'Right,' said the sergeant. 'It's like we thought. No signs of ground-based forces. We can a.s.sume the satellites are still in effect, so don't drop your cloaks. Looks like the enemy can bypa.s.s them anyway, but you've got to live in hope.'

There was a grumble of discontent from the troops. Not loud enough to be considered mutinous, naturally.

'And you can stop that, as well,' the sergeant growled. 'OK. The Time Lords say the enemy installation's over on the north side of the big ridge, and I'm not going to argue with them. It's shielded, so we'll need to find it for ourselves, the palm-scans aren't going to do us a lot of good. Any questions?'

n.o.body said anything.

'Great. So let's move. And stop staring at him like that. He's not going anywhere.'

More grumbling. Then more scrunching. The sound of marching feet.

They were walking away from him. Well, obviously they were walking away from him, it wasn't as if he were an indispensable part of the mission or anything. He was light infantry. Cannon fodder. Only here because he knew how to fire a staser without shaking his own arm off. One of a million stupid recruits who'd been primed to shoot at anything they were told to shoot at. The Gabrielidean military didn't like people who asked questions, and neither did the Time Lords.

No, he thought. No, not here. I know where I want to die, and it's not here, on some freezing alien rock n.o.body's even heard of. I don't want to leak out into the ground. I don't want to be a bioma.s.s popsicle. I want to die where it's warm. I want to die in the pool where I was born. I want to die like a Gabrielidean.

He opened his mouth to tell the Nth Platoon this, but all that came out from between his artificial lips was a long, high-pitched wail. If any of his comrades noticed it, they must have thought it was the wind, because he didn't hear any of them turn around. The scrunching faded away, became part of the planet's background noise.

He didn't have the energy to scream any more. He let his vocal cords go slack, and felt himself drifting off to sleep again.

Darkness.

He awoke to the sound of whispering. Not the normal sort of whispering, not the sort you could hear through the ears of a human suit. It sounded like it was trapped under the skin of the world, below the surface of everything you could see or feel. Words were trying to come up for air, but it felt like there was a layer of ice between him and them, hard as the ice under his back.

He was being discussed. He knew when people were talking about him, and they were talking about him now. A few of the sentences broke the surface, bobbed around on the edges of his hearing.

'...an ideal subject?' somebody asked.

'...is getting close now,' somebody else said.

'...makes no difference... until the Doctor... perfect opportunity...'

But it was too much of an effort, trying to understand them. His body was still oozing out of the suit, staining the snow pink underneath him. Soon, there'd be nothing left of him. He didn't have the energy to think about imaginary voices.

He let his senses sink back into the ice.

Darkness.

When he regained consciousness, he wasn't alone.

He couldn't see his visitor. His head was locked in position, the joints frozen in his neck. But there was someone pacing up and down behind him, shoes crunching against the snow. There was a tap-tap-tapping, the sound of a stick probing the ground, testing to see how solid it was.

Suddenly, the crunching stopped.

'Are you awake?' a voice asked.

He concentrated on the voice, but he didn't recognise it. It sounded like it came out of a humanoid mouth real humanoid, so it wasn't another Gabrielidean in a suit and it was tinged with an accent he couldn't quite place. There was no native life on this planet, he'd been told, and the enemy weren't supposed to have any troops here, only automatic defences. Did the voice belong to an alien, then? An outsider?

It took him a full minute to get the suit's vocal cords working. 'I'm awake,' he croaked.

The alien made a few more crunching sounds behind him. Crouching down, presumably. 'I wasn't expecting to find anybody here. The rest of your platoon's gone. I should think they're going to get help.'

He almost found that funny. Evidently, the alien was trying to rea.s.sure him, though he had no idea why.

'Who are you?' he asked.

'I'm an observer. A spectator. An interested party. Trust me, I'm not important.'

'You're a Time Lord?'

'Ah. Well, I'm not working for the High Council, if that's what you mean.'