I saw them tame the great central continent and aquaform it into a beautiful city a thousand miles wide. I saw them take control of the weather, of the land, of near-orbital s.p.a.ce. I even saw them begin to push back the great volcanoes girdling their world to make more living s.p.a.ce for themselves.

But something was wrong.

They were improving the quality of their life, the length of their life ... but no one yet had made provision to use the new science to save their species from extinction. The Astronomer Royal was still plotting out his new performance, as yet only planning rehearsals. It was as if they were deliberately ignoring the threat moving remorselessly through the Solar System. As if ignoring the problem would make it go away. They were wrong. I knew that the moment I spotted it, five hundred years into my incarceration. I knew it because that's what I had done, so many years ago.

Now I saw that, though he was still the oldest among them, the relative gap between the Astronomer Royal's experience and the general population was narrowing. Now more of the Cthalctose were living for longer. More were growing and maturing; learning about themselves and about their society. More were taking an interest in their future, in shaping their future.

The balance of power was shifting. The old way - of considering - was dying and the new way - of doing - was coming into its own.

At that moment my dreams turned to nightmares. Nightmares that lasted half a millennium.

I watched them build cities and blow them up and build them again. I watched them waste years improving their old s.p.a.ceships before realizing they should start again from new principles. I watched them realize, far too late, that they had no time to build enough new ships to escape their destruction.

I saw them propose and reject plan after desperate plan. I watched as they built force-field generators the size of asteroids and orbited them around the singularity to prevent it absorbing any more ma.s.s from the Solar System.

It was acting without thinking. Even the new science couldn't neutralize the force of gravity. In less than three hundred years half the Solar System had gone, replaced by a sh.e.l.l of solar matter the size of a brown dwarf which had formed with its inner surface just metres away from the Event Horizon.

Worse: buried deep beyond the reach of solar energy, the force-field generator power supplies would not last forever. In a few years the force field would collapse and half a solar system's worth of matter would drop, almost simultaneously, over the Event Horizon.

I had seen the results of that already.

A momentary sun. An irradiated planet. An extinct species - and a moon blasted out into s.p.a.ce carrying the seeds of life to destroy my own world.

In the last years the Cthalctose came to understand what I already knew. In desperation they united to expend their last resources and energy attempting to build a fleet of ships which could carry them to another world and save their lives. But it was too little, too late. In the end all they had time to do was return to the Astronomer Royal's original plan of building a terraforming platform on the Moon and argue about whose fault it was that they had failed to survive for the few remaining years before the end came.

I could have spared them even that waste of time.

I knew what was going to happen; I knew whose fault it was.

I had only ever meant to stop any of this from happening in the first place.

Now I saw the truth. Instead of saving two species from extinction I had been responsible for the destruction of both.

I watched it all happen, safe inside my force field. I watched the star bloom, I watched the Moon shift out of orbit on the start of its long journey, I watched them die. Vehicles, Providers, Engineers, even the old Astronomer Royal. I watched them settle into death and dissolve in the acid oceans, and finally, as the planet began to break up with tidal stresses, and the stasis-inducing chemicals leached out of my body, I slept.

I was shaken awake by an earthquake. The nurseries were blooming with fire, lava and acid met in a symphony of flame. The world was shaking itself apart. There was no one else alive, anywhere. The dreams were over.

Gone.

I had a sudden image in my head. An alleyway, black and cold under a starless sky, empty except for a paperback book - The Magician's Nephew - its pages rustling quietly in a dying wind, a whisper of sound that seemed to say, No more stories, Jason. Story time is over now.

I slipped Benny's ring on to my finger next to my own, and asked them both nicely if they would please take me home.

Chapter 11.

When I realized Jason had taken my ring, I sat down on the floor and tried to think. What was he going to do? It didn't take a genius to work that one out. We had both experienced the Astronomer Royal's SurroundSound SuperMarionation History of the Cthalctose Species. Now Jason had both rings. I'd bet my life savings to an ice lolly he was trying to change things. I didn't bother waiting around for the changes I knew were not going to come. I spared a few minutes hoping he wouldn't get himself killed learning this particular lesson, then went to help the soldiers try to find Tammuz.

We searched for an hour. Nothing. I went back to the TARDIS. It was looking particularly unwell. Inside, things were even worse. The Doctor, now wearing one of his own force-field emitters was head and shoulders deep in a panel beneath the Time Rotor. All I could see were his little legs sticking out from beneath the console. I am sure he didn't hear me come in, but he waggled his left foot in my general direction anyway.

'Ah. Benny. Soldering iron.'

'Pardon?'

The foot waggled in the general direction of a mechanic's toolkit, the metal compartments spread open like an inverted pyramid. 'Soldering iron. Flux.

Solder. Thank you so much.'

I rummaged in the kit and handed the items to the disembodied hand which stuck out briefly from under the console. 'You've come to tell me Jason's gone.'

'How did you know?'

'Ah. Telepathic connection between the rings and the TARDIS. Hand me a five-and-three-tenths spanner would you?'

I pa.s.sed him the spanner. 'Spanner? Soldering iron? This is all a little crude, isn't it?'

'Some situations call for subtle finesse, some - there was a loud banging noise '- for the bludgeon. There. That's got it. Is there a small screwdriver in there? No. No, sorry. Make that a spokeshave.'

'A spokeshave? What are you doing under there, building a cupboard?' He made a sort of non-committal grunting noise. 'Are you sure you wouldn't just like the whole kit?'

'Actually that's not such a bad idea. What are you going to do about Jason?'

I pushed the kit over to him. 'Not much I can do, is there?' He hooked the handle with his foot and the kit vanished beneath the console.

'Depends what you mean by "not much".'

'I don't understand.'

'There are always choices.' There was another loud thump, a m.u.f.fled yelp and the Doctor slid out from beneath the console, sucking his thumb. He sprang to his feet and dusted himself down, pulling an apparently endless succession of tools from his pockets and jamming them back into the toolkit.

'What if there aren't any choices?'

'Invent some. That's what Jason has done.'

I tried to curb my anger at my husband's stupidity. 'That's what he thinks he's done?'

'No. That's what he has done. Everyone in the Universe has free will, Benny. Predestination wouldn't work otherwise.'

'Er. Sorry?'

'Look at it this way. You and I both know that Jason has gone back in time to try to stop what's already happened from happening, right?'

'Right.'

'But we both know he's going to fail, right?'

'Right.'

'And that in failing he will be responsible for the entire situation he tried to prevent.'

'Right.'

'But he doesn't know that, does he?' 'No.'

'No. Or he wouldn't have bothered to try to stop it in the first place, would he?'

'Er, no. I suppose not.'

'Of course he wouldn't. There wouldn't have been any point, would there?

But if he hadn't gone then what actually happened wouldn't have happened at all, and you'd probably still be drinking warm Pepsis in Dogubayazit instead of having this conversation.'

'But that would be a paradox.'

'Exactly.'

'But paradoxes are impossible.'

'I prefer to use the word embarra.s.sing.' He winked conspiratorially. 'They're less threatening that way?'

'Am I supposed to laugh at that?' 'Do you want to?'

'Would it make a difference?'

'Probably not.'

I chuckled. 'So what's your point?'

'Only this: that by exercising his free will, Jason has in fact become an agent of predestination.'

'And that's what you wanted to tell me? That my husband is probably responsible for the destruction of the Earth and the deaths of countless millions, and that I should try to understand and forgive him?'

The Doctor looked up from the console with a surprised expression on his face. 'Actually no, I wanted to tell you Jason is guilty and upset about not living up to your expectations of him as a husband and father, and that you should try to understand and forgive him.' He thought for a moment,then looked even more surprised. 'But I suppose it works both ways.' He beamed. 'Actually, that's quite clever. Did you see where I put the soldering iron?'

'In the toolbox.'

'Ah. Thanks.'

A thought occurred to me. 'How did you know I'm -'

He looked up. 'Are you?'

I thought about my reply very carefully. 'So what's the matter with the TARDIS?'

He shrugged. 'Long story. Had to adjust the dimensional stabilizer so Chris could fly Sven's chopper in through the doors to avoid a nuclear explosion.

Thing is, the chopper was infected with Agent Yellow. I thought I'd deleted the infected area, but apparently I missed a bit.'

'Missed a bit?'

'Mmm, that's right.' The Doctor chewed thoughtfully on the soldering iron, yelped, flipped it over, stuck it back in his mouth and chewed again. 'Either that or. . .' He thumped the console suddenly. :Thhuh uhhh!' He spat out the soldering iron, caught it in mid air and flipped it back into the toolkit.

'That's it! Jason and Chris were infected, but they're still alive? They must be carriers.'

'Is he - I mean, are they going to die?'

'Probably not. But you never can tell. But even if they don't die, they'll just spread the infection everywhere they go. Unless they live the rest of their lives in a force field.' The Doctor looked at me suddenly. 'How exactly did Jason "go"?'

'He took my ring.'

'He touched you?'

'I suppose so. I -' I stopped.

The Doctor said grimly, 'If he is a carrier and he's infected the TARDIS, then . . .'

It didn't take a genius to finish his thought. 'Everyone here is infected as well.'

I was about to get really nasty when Chris bounced into the TARDIS and said, 'Hi. The umbrella's working fine. I've disarmed the warheads.'

I frowned. 'Talk about losing a shilling and finding sixpence.'

Chris framed a reply and was about to speak when the door opened again.

Jason was standing there. He looked gaunt, shocked, for all the world on the verge of a breakdown. My heart leapt out for him but somehow I just couldn't move.

He said, 'Has anyone got any food? I haven't eaten in a thousand years.'

My sympathy vanished almost immediately.

The Doctor said, 'Gentlemen, brace yourselves. I have some bad news ...

and I have some bad news. Which do you want first?'

The Doctor went through it all one more time for Chris and Jason. At the end of it Chris looked faintly puzzled. 'There was something Roz said ... in the helicopter ... I can't quite ...'

Jason added, far too importantly, I thought, 'I was serious about that food.

You've no idea what I've been through.'

The fact that both of them seemed for a moment incapable of addressing the real problem - or even of being aware that they were the problem - just made me see red. Of course I picked on Jason.