Growls coming nearer, the patter of tiny feet and the snapping of sharp teeth-Artery. I squeeze my eyes shut, silently willing on the demon child.

"No," Lord Loss stops him. "To me."

I reluctantly open my eyes and look up. Lord Loss's face is glowing with sad satisfaction. Artery is making his way to his master's side, glowering. Behind them I spot Beranabus, looking old and frail, but triumphant. Kernel is still locked in combat with Spine.

Dervish puts his ear to Bill-E's chest. Listens a few seconds, then raises his face-his eyes are those of a haunted man. "He's-"

"Shut up," I sob before he finishes the sentence. Then, softer, "I had to. Not to stop the Demonata, but for his sake. He would have suffered worse than any of us. They'd have used him. He couldn't have died. He'd have been stuck down here, tormented by demons, knowing he'd handed our world to them. I couldn't let that happen. If there'd been any other way..."

Dervish finds my left hand and squeezes reassuringly. We both weep fresh tears.

"Delicious," Lord Loss murmurs, savouring our sorrow. "I wish this moment could last an eternity. It was worth having our plans thwarted. My brethren will break through another time. This world cannot stand against the Demonata much longer. There is a force in motion which cannot be repelled. That is why I pledged myself to the cause of destruction, much as I delight in humanity's enduring pain. Things might have gone badly for me if I'd resisted. But this is the best of both universes. You have done me a great favour tonight. I am almost tempted to let you all live... but there are scores to be settled. A few more minutes to relish your agony, then I shall extract my long overdue retribution."

"Yeah, yeah," I mutter halfheartedly, brushing Bill-E's hair back from his eyes. I don't care about the demon master's threats. I don't care about anything except the fact that I've killed my brother and life can never hold any pleasure for me again. Better to die sooner rather than later.

But part of me cares. It stirs in response to Lord Loss's pledge. Energy slides down my arms to my hands. I call it back, but it doesn't respond. It's a strange type of energy, not like the magic I used to fight the demons (or kill Bill-E). This is more like the power I felt when I thought all was lost, when I distorted the laws of time and...

"We can go back!" I gasp, bolting upright. "We can travel into the past again and save Bill-E!"

Lord Loss hisses, not liking the sound of that. His six arms rise and he glides closer. Laughing hysterically, I bring my own hands up, aim at him and unleash the energy which has been buzzing at the tips of my fingers for the last few seconds. I expect a huge ball of magic to knock the demon master back, then shoot us into the past, where I can make things right. But the magic comes out in a stream, not a sudden burst. And it doesn't fly in Lord Loss's direction. Instead it flows into Bill-E.

I try redirecting the energy, but I can't control it. The magic seeps out of me and into my dead brother. Lord Loss is watching uncertainly, frowning, perhaps wondering if this is part of a time-travelling spell. Beranabus is dragging himself towards us, not willing to die without a fight. Dervish is still weeping over Bill-E, oblivious to all that's going on.

And then Bill-E moves.

At first I think it's just Dervish jolting the body, but then I see Bill-E's fingers shake and curl inwards. His lips part. He shudders. His eyes flicker open.

"What is this?" Lord Loss growls. "Regeneration? It cannot be. I felt his soul depart."

"Billy?" Dervish cries, unable to believe it, falling backwards as Bill-E sits up and looks around.

"Bill-E!" I yell with excitement, grasping his arms, squeezing hard, delight taking the place of dread. Somehow I've brought him back. I've used magic to restore his life. Everything's OK. We've beaten the demons and saved Bill-E. How's that for a night's work! "I'm so sorry for what I did, but there was no other way. But it doesn't matter now. You're alive. We whupped their ugly hides and..."

I stop. Bill-E's looking at me curiously, as if he doesn't know me. And his face is strange. His skin is bubbling, rippling, shimmering, a bit like Juni's did when her face changed. Then he opens his mouth and speaks, and I can't understand a word he's saying, because he's speaking the language of the girl in the rocks. They're Bec's words, not Bill-E's.

Lord Loss gasps. "You! No! I will not let you-"

Bill-E's right hand points at the demon master. He shouts something in Bec's language and Lord Loss screeches, "Artery! Attack!" The hell-child leaps and Bill-E's hand snaps round. A ball of energy surges from his fingers and Artery explodes into a thousand shredded pieces. He'll never recover from that. The hell-child has been finally, savagely, beautifully killed.

Bill-E stands. His flesh is still changing. The bones seem to be altering too. His eyes and ears. His whole face. Softening. Narrowing. Becoming more... feminine.

Lord Loss stares at the remains of his dead familiar. Trembles with a mixture of rage and fear. "You should not have come back, girl," he snarls. "This is wrong. You are asking for trouble, and be assured-it will find you."

Bill-E laughs in a way he never laughed before. Catches sight of Spine and waves a hand at the demon-it melts, screaming shrilly, a pool of gristle-speckled liquid within seconds, leaving Kernel to grapple around uncertainly and wonder what happened to his foe.

Bill-E faces Lord Loss again. His face is unrecognisable. His body too-he's smaller and his clothes are hanging loosely on his frame. I'd think I was going mad, but Dervish and Beranabus see it too. Their faces are contorted with bewilderment.

He speaks again and this time I hear the girl's accent as clearly as I heard it when she spoke to me from within the heart of the rock. Lord Loss trembles, then scowls. "So be it. Perhaps you are right-this is not our time. But it will come, be sure of that. And you won't have to wait another millennium and a half for it!"

The demon master draws himself up straight, then glares at me. "Enjoy your victory, Grubitsch. But remember-the end of the world is coming and there is nothing you or that apprentice priestess can do to stop it. Remember this also-you killed your brother. He died by your hand. How do you think you will sleep tonight? And all the-"

Bill-E barks a short spell. The strips of flesh at the end of the demon master's legs are suddenly alive with rats. Lord Loss squeals, slaps several of them away, then darts to the stalagmite where the body of Juni Swan is impaled. Ripping her corpse free, he cradles her to his chest, snarls hatefully at all of us in the cave, then launches himself at the crack in the rock-now just a thin line a few centimetres wide. He hits it hard and uses magic to squeeze through. Even so, the walls of the crack scrape much of his and Juni's flesh away, and the rats on Lord Loss's legs are knocked loose. They fall on the floor, turn in puzzled circles for a second or two, then tear away, heading for the surface, back to wherever Bill-E summoned them from.

Except it wasn't Bill-E who made the rats materialise. It was Bec. And I realise, as I watch him looking down at himself, curiously touching his chest and face, that Bill-E's as dead as ever. The girl from the far distant past has taken control of his body and is transforming it into her own.

A couple of hours later. Home. Sitting in the TV room with Dervish and Kernel. Kernel is asleep, moaning as he dreams, pain coming at last. Beranabus and Bill-E... no, Beranabus and Bec are in another room, having a lengthy heart-to-heart. The magician was ecstatic when he understood what was happening. He practically burst with excitement. Hugged her hard, weeping happily, kissing her face. And she stood there, hugging him back, crying too, repeating one word over and over-"Bran!"

Dervish and I haven't said anything to each other. He's staring off into space, his face a mess of dried tears. Every so often he shakes his head or makes a soft grunting noise. That's as close as we've come to communication.

I don't know what to feel. I've saved the world from the Demonata, but at what cost? To kill your own brother... Nobody should ever have to suffer such a cruel fate. I'm already wishing I could go back and change it. Maybe Bill-E would be better off alive and suffering than dead and gone. Did I have the right to make that choice for him? I don't know.

And maybe I can go back. I haven't discussed it with Beranabus yet, but I will, as soon as he's through talking with Bec. Find a way to travel back in time like we did before. Stop any of it from happening. Snatch Bill-E from Juni's clutches. Never open the entrance to the cave. I don't see why we can't. We did it once. I don't care what Beranabus said about waves and trains reaching the end of the line-there must be a way to do it again.

Eventually, as the sun rises on a normal day, lighting up a world unaware of how close it came to toppling into an abyss of demonic damnation, Beranabus and Bec return. There's almost nothing of Bill-E left. The girl has taken over completely, remoulding his body in her own image. Even his hair has turned a dark red colour. One or two small traces of my brother remain-she walks like he did, and her left eyelid hangs a fraction lower than her right-but I'm sure those traits will vanish too.

"Sorry we were such an age," Beranabus says, sitting opposite Dervish. "Loads to talk about. We've cut it short as it is, only covered the more important issues."

Bec stares at the couch, then sits on the floor close to the magician's legs. She looks at me with worried eyes. "I hope you do not mind that I took this body."

I blink. "You can speak our language now?"

"A spell," she replies. "Beranabus taught me. I'm speaking in my own tongue, but it allows me to be understood by others." She sighs. "If I could have worked such a spell when we first made contact, things would have been much simpler."

"I'd normally say there was no point worrying about the past..." I begin, but Dervish cuts me off.

"Who are you?" he shouts. "What the hell have you done with Billy?"

"Billy's dead," Beranabus says. "This is Bec, an old friend of mine."

"No!" Dervish yells, lurching to his feet. "That's Billy's body. She stole it. I saw her. I want it back." His hands bunch into fists.

"I apologise, but I cannot give it back," Bec says quietly.

"Even if she could, what would be the point?" Beranabus chips in, roughly but typically. "The boy's dead. Bec took his lifeless flesh and filled it with her spirit. If she vacated it again, you'd only have a dead child on your hands."

"I want him back," Dervish snarls, eyes wild.

"I understand," Bec says solemnly. "You wish to bury him."

"No!" Dervish howls. "I want to hold him and tell him how much I love him. I want to..." He breaks down and slumps sideways, sobbing into the cushions. I long to go to my uncle, hold him, help him. But there are too many questions which must be answered. As cruel as it sounds, Dervish will have to wait.

"How did you do it?" I ask quietly.

"Which part?" Bec replies.

"The last bit-taking over Bill-E's body."

She shrugs. "I could see everything that was happening. I came back inside you-when we worked together to bend time, I joined with your flesh and mind. I could have stayed there within you, hidden away, and I meant to. But when I saw what Lord Loss was going to do, and realised you wouldn't defend yourself, I had to act. I wasn't sure if I could use the dead boy's flesh. Even if I could, I only planned to inhabit it temporarily-I thought I could possess it, drive Lord Loss away, then leave it again.

"But, to my shock, the body accepted me. More than that-I was able to transform it and recreate my own form. I needn't have-I could have kept your brother's shape-but I wouldn't have been comfortable that way and I don't think you would have been either."

"So this is your body now?" I ask. "You're alive after all that time in the cave? Free to grow and live like any other person?"

The girl shrugs again and glances at Beranabus.

"We don't know," the magician says softly, touching Bec's short red hair. "This body might age and develop naturally-or it might not. We'll have to wait and see. Only time will tell."

"Speaking of time..." I lean forward anxiously. This was what I wanted to ask about first, but it wouldn't have been polite to barge straight in with it. "How did you bring us back from the future?"

Bec shakes her head softly. "I didn't. We did it-Kernel, you and I."

"But you started it. You knew the spells. You were in control."

Again she shakes her head. "It was the Kah-Gash. Although we are parts of the weapon, it has a mind of its own. When we joined, our magic became the magic of the Kah-Gash. It told us how to unite minds and forces. It used us. Like you, I didn't know what it was attempting to do. The time travel came as much of a surprise to me as it did to you."

Bec looks around, staring at the chairs, the windows, the TV. This is all new to her. Unimaginable. She comes from a time when the world was much simpler. She's itching to explore, ask questions, make sense of all the weird shapes and objects. But I can't let this pass.

"Do you remember the spells?" I press. "Could we do it again?"

She thinks a moment and frowns. "It's strange. Normally I only have to hear something once-I have a perfect memory and never forget anything. But in this instance I have only the vaguest recollection of the spells. I couldn't repeat them."

"You could try," I insist.

She nods. "If you prompt me, I will do my best. But I cannot start without your help. You would have to show me the way, like you did before."

"Grubbs," Beranabus says, "you can't go back again."

"Why not?" I shout. Dervish looks up, startled by the ferocity of my tone. "Why the hell can't I?"

"The Kah-Gash reversed time because the world faced annihilation and there was no other way," Beranabus says calmly. "But it was a massive, perilous undertaking. If it had gone awry, the result would have been chaos, timelessness, maybe the destruction of both universes. You can't take such a risk again, just for the sake of one boy."

"That one boy means more to me than all the others in the world put together," I snarl.

"Maybe," Beranabus replies, "but he means nothing to the Kah-Gash. If he did, you wouldn't be sitting here arguing-you'd be spitting out spells, trying to find the energy to take you back. You set events in motion last time. You were the first to act. If you want to do it again, go ahead."

"I don't know how!" I howl.

"Ask the Kah-Gash," Bec says. "It spoke to us before and directed us. It's like a person. You're able to talk to it. Ask and see how it responds."

"I don't think-" Beranabus begins.

"Let him," Bec insists. "If he feels he must do this, and if he can, it's not our place to stand in his way."

I stare at her uncertainly, then close my eyes and focus. I search for the magic and quickly find it, an energy and consciousness. There are no barriers between us now. I'll never have trouble finding it again. It's as much a part of me as the oxygen in my lungs.

I tell the magic-the Kah-Gash-what I want. I beg it for help. But there's no answer. I guessed there wouldn't be. Now that we're one, I've begun to understand that other, mysterious part of myself. Beranabus is right. It won't let me smash the structures of time just to save Bill-E.

"Even if you could phrase the spells," Beranabus says as I open my eyes, tears flooding down my cheeks, "there isn't a source to track back to. In this time, the tunnel hasn't been opened. There's no river of energy to ride back on."

"We could find another place where demons broke through," I moan.

"No," Beranabus says. "You'd need an open tunnel, but there aren't any."

"Maybe it doesn't have to be open," I whisper-one final, desperate attempt. "We could try a tunnel that's been closed. The energy might be trapped there, held in place, like in a battery or power cell."

"Maybe," Beranabus agrees. "But even if the energy was present, and you could unlock it, you'd have to follow the unleashed river of power back to its origin. I doubt it's possible to set limits, to travel back just a day, a week or a month."

"So what?" I sob. "We'll ride it back to the start and wait. I don't care."

Beranabus smiles softly. "The last tunnel that was anything near to this in size was closed more than three hundred years ago."

"Three..." I mutter, feeling the last sliver of hope die within me.

"Let it go, Grubbs," Beranabus says. "Your brother's dead and you can't bring him back. There's no way around it. You'll drive yourself mad if you can't accept that."

"Maybe that wouldn't be so bad," I sigh, then sit there, crying, saying my silent farewells to poor, unfortunate Bill-E Spleen-R.I.-bloody-P.