At first I think the world and universe have been utterly destroyed and I'm just imagining the laughter. But then the blackness clears slightly. I realise I have eyes again. Blinking, I look around, but can't make out much. It's night and I'm in the middle of a cluster of trees. It's not especially dark-the gleam of a full moon seeps through the branches of the trees-but it's hard to adjust or focus. My mind's spinning crazily in a bewildered whir.

"What happened?" Beranabus croaks, rising from a spot nearby. Kernel lies at the magician's feet, groaning, cradling his head in his hands. "Where are we?"

"I don't know," I whisper. My ears are searching for something. I'm not sure what it is, until after a few seconds it sinks in-the girl's voice has gone.

Kernel mutters something, then bolts upright, screaming. "My eyes!" he howls. "The maggots! My eyes! I can't-"

Beranabus covers his assistant's mouth and whispers words of magic, a spell to ease the pain. Kernel thrashes wildly, then regains control and stops struggling, though his chest continues to rise and fall rapidly.

Beranabus removes his hand. "Are you going to be all right?"

"My eyes..." Kernel moans.

"Gone," Beranabus says bluntly.

"But... we must... there has to be some way..."

"No. They're ruined. But don't worry-magic will compensate. You won't be entirely helpless." Beranabus squeezes the back of Kernel's neck. "We might even be able to knock together a pair of replacements when we return to the demon universe. If the gods are truly with us, you'll still be able to see the patches of light and create windows."

"Like I give a damn about that!" Kernel snaps sourly, but Beranabus ignores the hostility.

"Peace for a few minutes," the magician says. "I need to determine where we are."

He turns in a slow circle, eyes closed, breathing softly, trying to pinpoint our position. I know I should keep silent and wait for him to finish, but I can't. "What did she do to us? The ground breaking apart and rising... the sky and funnel... the lights and windows... the noise and pain. What was all that about?"

"How should I know?" Beranabus growls. "Maybe she was trying to destroy the demons and the spell got out of hand."

"But the sky! Did you see it? How did she do that? What-"

"Quiet!" Beranabus barks, opening an eye to glare at me. "How can I concentrate with you throwing stupid questions at me?"

"But she tore up the ground!" I shout. "She reversed gravity and brought the sky crashing down. And then she sent us... where? Is this Earth? A demon world? Are we dead?"

"I don't know," Beranabus sighs. "I don't know where this is or how she sent us here- teleportation, I suppose, but I've never seen it done that way before. But I know why she did it." He hesitates, then opens the other eye and looks at me with a shamed grimace. "I made another mistake. There have been far too many lately. I missed the sacrifice being made in the cave. I was wrong about Lord Loss not wanting to reopen the tunnel. And now I know my plan to close it was flawed.

"I told the Disciples that if we collapsed the walls of the tunnel, victory would be ours. The demons would be sucked back to their own universe. That's how it happened in the past. I assumed the rules would apply the same way in the present.

"Bec told me they wouldn't."

"You mean, even if we'd succeeded, we wouldn't have got rid of the demons?" I ask quietly.

"We'd have stopped others from crossing," he says. "And those here would have lost much of their power. But the world has changed. There's less magic in the air. My spells wouldn't have dislodged the demons. The masters would have remained and even weakened they'd have had enough strength to crush humanity. I don't think all of the Demonata were aware of that-they certainly didn't act like they were-but Bec knew we were doomed. To spare us, she worked a spell with you and Kernel to get us out, so we could regroup and try again."

"What's there to try?" I sob. "If we couldn't send them back this time, with all the Disciples to back us up... if destroying the tunnel won't work..."

"There must be a way," Beranabus mutters. "That's why I have to focus. Time's precious. Bec gave the demons a taste of their own hellish magic, but there's no guarantee that those sucked up into the sky are dead. Even if they are, the tunnel's still open. More can cross. We need to return and block their way. So be quiet and let me get my bearings. You can ask all the questions you want after that."

He closes his eyes and turns again, reaching out with all his senses. Kernel has dragged himself away to sit against a tree. He's exploring the empty sockets of his eyes with trembling fingers, picking out some dead maggots caught in the corners. I hobble over to check on him, to help if I can, to comfort him if he'll let me.

Then I see the rocks.

My eyes have adjusted and the light from the moon is strong, even under the cover of the trees. I can't miss the rocks. They lie scattered everywhere, but a lot are piled up on my left in a large mound. They can't be real. It isn't possible. I must be imagining them. Except I'm not. The magic inside me says they're genuine. It's smug. Confident. Triumphant.

"Beranabus."

"Grubbs!" he yells angrily. "I told you not to-"

"I know where we are."

He opens his eyes a fraction, suspiciously. "Where?"

"You don't need magic. Just look." I point to the rocks.

Beranabus frowns. Then he realises he's seen the mound before and his jaw drops. "No," he croaks. "It can't be. This is a trick. Or somewhere that looks like..."

"No." I walk across, pick up one of the smaller rocks, then lob it down the hole on the other side of the mound-the mouth of an all too familiar cave. "We haven't gone anywhere. We're still in Carcery Vale."

Beranabus is striding around the hole, squinting at it, studying it from every possible angle. Every so often he stops, mumbles to himself, shuffles towards the hole, then starts marching again.

I'm with Kernel. I've wiped away the worst of the muck from around his eyes, using leaves and forest water. "How are you feeling?" I ask.

"There's not much pain," he says, "but there will be. You can delay it in circumstances like these, but not indefinitely. I'll need hospital treatment when the spell wears off. Assuming any hospitals are left..." His head turns left, then right. "Is it day or night?"

"Night."

"I thought so. But it was day when we attacked. I didn't think I'd been unconscious that long."

"You weren't."

"Then..." He leaves the question hanging.

"We don't know," I tell him. "Beranabus is trying to figure it out."

Kernel nods slowly. "How do I look?" he asks.

I stare into the vacant pits where his eyes once were. They're peppered with dead maggots. A few are only half visible, their heads and upper bodies buried in the dark flesh and bone of his sockets. "Fine," I lie.

Beranabus begins to laugh. I think he's laughing at my lie and I turn on him angrily. But then I see that he didn't even hear what I said.

"Of course," he chortles. "It's the only answer. There's just one way she could have channelled that much power, to such an effect. You and Bec are the other two pieces. That's the only thing that makes..."

He mumbles his way back into silence. I say nothing, waiting for him to get it clear in his head, so he can explain it to me in simple terms. I study him while I'm waiting. He looks weird minus his beard and hair, naked as the day he was born. I guess I look pretty strange too, as bare and hairless as an egg. I'd feel awkward any other time, but things have gone so crazy within the last hour, I'm not bothered by my ultra-smooth nudity.

Beranabus glances up and waves a hand at the trees. Their branches part, granting him an unobstructed view of the moon and surrounding sky. His eyes dart from the moon to the stars. I can practically hear his brain whirring as he performs silent calculations. Then the branches rustle back together and he laughs again. "I knew it!"

Beranabus bounds over to where Kernel and I are waiting. He crouches beside us, beaming like a proud father whose wife has just given birth. "The prime rule of magic-anything is possible. It's the first thing I teach my assistants, but when you've been doing it as long as I have, it's easy to forget your own advice. Just because something hasn't been done before, and just because the power involved is way beyond that of even the greatest demon master, doesn't mean it can't be done. Bec must have realised what she really was. She spent centuries preparing herself, waiting patiently...

"Or maybe she only saw how to do it during the battle. Maybe you were the catalyst, Grubbs. Or Kernel. Though I don't think so-he came last to the union, didn't he? I don't suppose it really matters. Maybe Bec can tell us, assuming she's..." He stops. "Yes, she must be alive-I mean, her ghost must still be here. It has to be. At least, I suppose..." He trails off into silence again.

"In your own time, Beranabus," I mutter impatiently. "Whenever you're ready."

He flashes me a crazy smile. "This is so extraordinary. Every time I think about it, I discover something new. We've taken an immense leap forwards-well, a leap backwards if you want to be pedantic. It's like going from the first stone wheel to the first manned flight in the space of one incredible day, one amazing spell. This requires years of study and analysis. We have to figure out how the three of you did it, how to control the power, what else we can do. That will-"

"I'm going to hit you if you don't stop babbling," I warn him. "Tell us what you know-or what you guess," I add quickly as he opens his mouth to start telling me he doesn't know anything really.

"I know you're in the dark, I know you want answers, just as much as I do. But..." He stops, focuses, takes a deep breath. "You asked me a question once, Kernel. It's a question most Disciples have asked, normally not long after I've told them that with magic anything is possible. Can you remember what it was?"

"I'm in no mood to solve riddles," Kernel sighs. "I just want my eyes back. Can you do that for me?"

"Not now," Beranabus huffs, waving the question away. "Think, boy. You were telling me about your early life, the night you created your first window and stepped into the universe of the Demonata. You said all your troubles started then, that if you could go back and stop yourself, everything would be fine. You asked me if-"

"No!" Kernel grunts. "It can't be."

"That's what I thought at first," Beranabus chuckles.

"But you said we couldn't!" Kernel protests.

"And I was right. Nobody ever had, and I didn't think anyone could. But now we have. You, Bec and Grubbs did it. You broke the final barrier. I never thought it could happen. I gave up on the notion long, long ago. When you've seen as much of-"

"What is it?" I cut in sharply, furious with ignorance. "What's the big secret? What question did Kernel ask?"

"The one they all ask eventually," Beranabus smiles. "The one you would have put to me if you'd been with me a little longer, when you looked back on all the times you went wrong, wondered how things would have turned out if you'd done this or that differently, gone down one path instead of another."

Beranabus stops, glances up at the trees and the moon beyond, as if to reconfirm it before saying it out loud. When he looks at me again, the smile's still there, but shaky, as if he's not sure whether he should be smiling or not. And he says, very softly, "Kernel asked me if it was possible to travel back in time."

A shocked moment of incredulous silence. Then I laugh. "Good one. You almost had me going. Now quit with the jokes and-"

"This isn't a joke," Beranabus says.

"You're trying to tell me we've returned to the past, like in some bad science-fiction film?"

"No," Kernel giggles, then hits me with the punchline. "Like in some very good science-fiction film."

"Don't," I mutter. "Things are mad enough without you two veering off at some ludicrous angle. We need to think about this logically, go through what happened step by step, so we can understand. Wild speculation won't get us anywhere."

"It's not wild," Beranabus says. "And it's not speculation. It's fact."

"I don't accept that. You're wrong."

"How else can you explain this?" He points to the hole, the rocks, the trees.

"It's an illusion. Our minds have conjured it up or Bec fed the image to us to spare us the real, grisly truth. It happened to me before, in Slawter. Maybe we're lying by the cave entrance, unconscious, demons ravaging our bodies, and this is our only way out of the pain. Or we've gone into the universe of the Demonata and created this scene ourselves. Hell, maybe we're dead and this is what we've chosen for the afterlife."

"We're not dead," Kernel says. "And we're not imagining this. I'd have given myself eyes if we were."

"Time travel's impossible," I say slowly, as if explaining something obvious to a young child.

"So is flying," Beranabus says, "but you've soared like a bird."

"That's different," I snap. "What you're talking about..." I shake my head.

"How did it happen?" Kernel asks. "I believe you, Beranabus-at least I think I do but how? You always said the past was the one thing we could never change."

"It is. I mean, it was. Demons can't do it. Magicians certainly can't. But the Kah-Gash..."

Kernel draws his breath in sharply. "Are you sure?"

"It has to be," Beranabus insists. "The ultimate power... the ability to destroy an entire universe... Why not the potential to reverse time too?"

"But if you're right, that means..."

"Grubbs and Bec were the missing pieces. And there must have only been three. It couldn't have worked unless all the pieces were assembled. At least I don't think it could..." He frowns.

"What the hell are you talking about?" I hiss. "What's a Car Gash?"

"Kah-Gash," Kernel corrects me. He's trembling, but not from the pain or cold. "It's a mythical weapon. You're meant to be able to destroy a universe with it, ours or the Demonata's. It was split into an unknown number of pieces millions or billions of years ago. Various demons and magicians have searched for it since then, without success. Thirty years ago we discovered one of the pieces. In me."

"You'd been implanted with something?"

"No. I am a piece of the Kah-Gash."

"I don't understand. How can you be part of a weapon? You're human."

"I'm magical," he disagrees. "The Kah-Gash is a weapon of magic, not physics. It can take the form of anything it chooses."

I think that through, putting it together with what they were saying a few minutes ago. "You believe Bec and I are part of this weapon too?"

"You have to be," Beranabus says. "The stars don't lie-we've gone back in time, to the night the tunnel was reopened. You three did it. We saw it happening. No force in either universe could have accomplished that, except the Kah-Gash."

"How?" Kernel whispers. "And why? If this is the work of the Kah-Gash, where did it find the energy to alter the flow of time? And why bring us back to this specific moment? Why stop here, not a hundred years ago or a million? Why not shatter the laws of time entirely?"

Beranabus scratches the back of his neck. "What did you feel when it was happening?" he asks.

Kernel shrugs. "Great power flowing into me."

"From where?"

"All around."

"Grubbs? Can you be any more specific?"

"The ground," I mutter. "The power came from the rocks, from beneath."

"And did it flow into you or through you?"

"What's the difference?"

"You'd have exploded if you drew in that much energy and didn't let it out," Beranabus says. "You had to channel the magic. But where to? The demons? The sky? Where?"

"The cave," Kernel answers after several seconds of thoughtful silence. "The power came from the ground, then went through us, back down into the rock, to the cave... the tunnel."

"Yes," I agree, thinking back.

Beranabus smiles. "The Kah-Gash-you, Kernel and Bec-acted as a kind of magnifying lens. You drew energy from the tunnel, then focused it back." He goes to stroke his beard, realises he doesn't have one and taps his chin instead. "I can't be sure-maybe I never will be-but this is how I think it worked.

"Opening a window between the Demonata's universe and ours is like making a hole in a dam- matter flows from their universe to ours, generating energy. Space, time, gravity, the forces which hold our universes together... they seep across every time a demon or one of us makes a rip.

"Windows are small, temporary. The energy generated is minimal. But in this case a tunnel was created, open twenty-four hours a day. A huge river of magic flowed through. You three tapped into that. No... you must have done more than tap into it. You..." He clicks his fingers. "You rode it! It was like a wave of energy. You caught the wave and rode it back to its source, converting and channelling it at the same time."

"Rode it back to its source?" Kernel echoes. "You mean back to the universe of the Demonata?"

"No," Beranabus says. "You followed the wave back in time, transforming it and eradicating it, back to when the tunnel was created." He looks at me, his eyes bright with excitement. "This is the night of the full moon. The night Lord Loss returned to Carcery Vale. The Kah-Gash brought us back in time to the night when the tunnel was reactivated, so that we could prevent it ever being opened in the first place!"

He seizes my hands and squeezes tight. "Don't you see? We've been given a second chance. Not just to heal the damage done by the demons, but to stop it happening at all."

"But... no... it can't..." I mutter, head spinning.

"Grubbs," Beranabus says softly. "At this time, Dervish and your brother are still alive. We can help them, but only if we accept this and act fast. Now, are you going to stand there denying what your senses tell you, or are you going to help me save the world and all the people you love?"

And when he puts it like that...