An uneasy mood. We're all uncomfortable. Even the gruff Shark, who believes in forcing people to work for the Disciples, isn't used to tyrants like Beranabus.

The magician comes over and sits with us. He scratches the sole of his left foot, then runs a hand through his hair and coughs. "Take no notice of Nadia's hysterics," he says. "She'll be all right when she calms down. We've had similar confrontations before. Although this is the first time she's threatened to kill me." He laughs harshly. Nobody smiles.

"This isn't the best of introductions, is it?" Beranabus notes, looking at me wryly. "You think I'm a heartless beast. But this is the way life is for me. I have no time for decency. I'm a demon killer. That's my sole purpose in life. I sleep soundly - on those rare occasions when I sleep -  because I know I'm doing the task that the universe charged me with." He points at my shoes. "You might want to get rid of those. You too, Shark and... Deviant?"

"Dervish."

"Aye. Dump the shoes. They block the flow of magic. Even the slightest advantage can be vital when you're faced with a demon and battling for your life. I'm assuming you two intend to stay and help?"

Shark and Dervish glance at each other edgily. I don't think either had planned to stay. Then Shark shrugs and raises an eyebrow. Dervish nods in answer and smiles weakly. They bend to untie their laces.

Beranabus studies me closely as I peel my socks off. "You're a strange one, Kernel Fleck. Normally, I can sense magic in those who possess an abundance of it, but I get almost nothing from you, even though you must be throbbing with power to open windows between worlds so swiftly."

"I don't think it's magic," I say shyly. "It's like a puzzle. I see lights and I'm able to slot them together when they pulse. That's the only difference between me and you. I can see the pieces of the window. You can't."

"Tell me about these lights," Beranabus says. "When you first noticed them and realised you could manipulate them."

"I've seen the lights all my life, but it was only on the needle of rock that I realised I could..." A memory kicks in and I come to a surprised stop. "No, that's not right. A year ago, I put lights together in my bedroom, stepped through the window and went missing for a few days." I can't believe I hadn't remembered that until now.

"Missing?" Beranabus sniffs.

"Yes. Nobody knew where I was. I don't know either. I can't remember what happened when I stepped through the window."

"Nothing at all?" Beranabus presses.

I think hard, but even though I now know that I must have crossed into this universe, my mind's a total blank. There's something about the window itself, before I stepped through, but the memory evades me. I shake my head.

Sharmila has been listening closely. She looks at Beranabus, troubled. "Does it not strike you as strange that of all the places Cadaver could have emerged, he turned up in that village? The home of the one boy in all the world who has a power which in some ways is greater than even your own."

"You think he went there for Kernel?" Beranabus frowns.

"Perhaps. When we turned up, maybe he thought we were protecting Kernel. So he took the brother instead, gambling that Kernel would chase after him."

"A trap," Beranabus says, nodding slowly. "Aye, it could be. Maybe we should forget about Cadaver and - "

"No!" I hiss. "Art's the only thing in this universe I'm interested in. I don't care if it's a trap -  I'm going to keep looking for him. Whether you help me or not. I know how now. I'll use a window to find him."

Beranabus smiles icily. "You could have done that as soon as you returned. But you didn't. Instead you searched for me. Because you need me to snatch your brother back. You can find him, but you can't fight for him. You want me to risk everything I have - for you. Do you expect me to do that without asking for anything in return?"

I glower at the magician, but what he says is true. I am asking him to risk his life to help me.

"I thought you had to search for this Cadaver demon anyway," Dervish says. "He's the one who can lead you to the weapon, right?"

"Perhaps not directly," Beranabus says. "Nadia's vision wasn't clear. She said the demon thief could guide us. But perhaps he's already done that."

"You think part of the Kah-Gash is here?" Sharmila asks, dubiously looking around at the yellowish demon world.

"No. I think Cadaver was only meant to provide us with the means of finding it." He fixes his gaze on me. "You're the true guide. Cadaver's role was to lead us to you. Now that we know about your talent, we can use it to search for the Kah-Gash. That's the deal - help me locate the fragments, then I'll help you get your brother back."

I stare at Beranabus nervously. It sounds like a fair trade, but I'm wary. Afraid of ending up like Nadia, a tool in the magician's hands, a slave. Nobody knows how many pieces the Kah-Gash was broken up into. It could be a handful or it could be a thousand.

"Help me rescue Art now," I barter. "Then I'll search for the weapon."

Beranabus shakes his head. "The Kah-Gash first. You won't have any reason to help me once you have your brother back. You could open a window and slip away from me any time you wished."

I think it over carefully, not wanting to tie myself to a deal which might backfire on me later. I've never had to bargain like this before. It's strange. Confusing. Frightening. But I force myself to concentrate and think all the options through.

"One piece," I say quietly. "I'll help you search for it. Then we go after Cadaver and Art. That's fair."

Beranabus scowls and starts to argue.

"He is right," Sharmila heads him off. "That is an equal exchange. An eye for an eye, so to speak."

Beranabus makes a grumbling sound. "It's not equal. That's like me saying I'll help you rescue one of your brother's legs. You want the whole boy - well, I want the whole Kah-Gash."

"But I could spend the rest of my life looking for all the pieces!" I cry.

Beranabus rolls his eyes. "Very well," he says reluctantly. "Find the first piece. Then we rescue your brother. Then you help me find the rest of it."

"No!" Sharmila snaps. "You can't ask that of him."

"I can and I did," Beranabus retorts without taking his eyes off me. "Of course, I can't hold you to that promise, but I'll trust you to keep your word if you give it."

I hesitate. My gaze slides to Nadia, still sitting with her back to us, crying. To spend years here like she has, fighting demons, never return home... Do I love Art that much? Would I sacrifice all that I have to save him?

"It may not take as long as you think," Beranabus says. "There might only be a few pieces of the Kah-Gash. Maybe we'll find them within weeks or months. Once I have the weapon, I'll be able to destroy the demon universe. You can go home. Lead a normal, happy, human life."

I nod slowly, deciding. "OK." Beranabus breaks into a smile. "But you've got to agree to help me even if I can't find the Kah-Gash."

The magician's smile vanishes. "Why wouldn't you be able to find it?"

"I don't know if I can search for objects. Maybe I can only open windows to people or demons. If I can find it, I will. But if I search and I can't, I want your word that you'll still help me."

Beranabus considers that. "Very well."

Solemnly, seriously, we shake on the deal. And I try hard not to think about the legend of Faust.

I move apart from the others. Study the patches of light, all sorts of sizes, shapes and colours. I try not to dwell on the deal. I have to put Art's needs before my own, then hope for the best later.

And if you have to spend the rest of your life in servitude to Beranabus? a voice says within me.

I can't worry about that now. What will be, will be. Art first - after the Kah-Gash.

I'm not sure how to look for it, since I've no idea what exactly it is that I'm searching for. I run the name through my thoughts, studying the lights, hoping some will pulse. But they don't.

I clear my thoughts and try another approach. I think about an object - a tree that I used to climb when I lived in the city. Dozens of lights pulse. I let the image of the tree fade, wait for the lights to return to normal, then experiment again, this time trying to think of an object I'm not familiar with.

It's not as easy as it sounds. I think of famous buildings, cities, Mount Everest. But while I haven't been to those places, I have an image of each inside my head, and when that image pops up, the lights start pulsing.

"Tell me the names of some strange places or things that I won't know about," I say to Beranabus and the others.

"Why?" Beranabus asks.

"Just do it. Please. It's important."

"The Taj Mahal," Sharmila says.

"No. I've seen pictures of that."

"My bedroom," Dervish says with a laugh.

"No. Something specific, with a unique name."

There's a pause, then Beranabus says softly, "Newgrange."

"Perfect!" I haven't the slightest idea what that means. Focusing on the word, I stare at the lights and murmur, "Newgrange, Newgrange, Newgrange." I keep repeating it, mind blank of images, having only the name to work with.

Several lights pulse, then others, and more drift towards me from points further away. I slot the patches together. When a deep blue window forms, I ask Beranabus to step through with me.

"Why are we going to Newgrange?" he asks.

"I'm testing my powers."

As soon as we emerge, I know we're back in the real world. It's a grey, wet day. Ahead of us stands a strange structure, a long, white brick wall with a doorway in it, a grass mound for a roof.

"Is that Newgrange?" I ask.

"Aye," Beranabus says, a soft smile on his lips. "It was built by the Old Creatures, beings of amazing magic. They kept this world safe from the Demonata for thousands of years. When they moved on, their power passed with them, leaving us open to attacks. I resented their passing when I was younger, but now I think they had to leave, that humans have a destiny of their own, which they must follow by themselves."

I don't really understand that, but it doesn't matter. What I know is that I can use the lights to search for objects which I'm not familiar with. Armed with that knowledge, I retreat through the window, to search once again for the mysterious Kah-Gash.

I spend several minutes running the word through my thoughts, but the lights don't respond. Not even a shimmer.

"Does the weapon have another name?" I ask Beranabus.

"Possibly. Demons speak many languages. But most refer to it as the Kah-Gash."

I try for maybe a quarter of an hour, then give up. "It's no good. I can't find it. Either it doesn't exist or I'm not able to locate it without further information."

Beranabus' face darkens. "If you're trying to play me for a fool..."

"I'm not. The lights aren't pulsing. I've tried my hardest, but nothing's happening."

"Maybe you need to give it more time," Beranabus suggests.

"That's not how it worked with the other windows. If I could find your weapon, the lights would have started pulsing by now. I can't do it."

Beranabus mutters something to himself and tugs irritably at his beard.

Sharmila is looking at me, head cocked, frowning. She starts to say something, then changes her mind and instead says, "We must search for Cadaver again."

"To rescue the child?" Beranabus sneers.

"Yes. But also to question the demon. Perhaps he knows another word for the Kah-Gash, which will enable Kernel to locate it."

"Or maybe Nadia was wrong," Beranabus says, glaring at his assistant's back. "Maybe this is a wild goose chase."

Sharmila shrugs. "Perhaps. But if we are to continue, it seems logical to make Cadaver our target."

Beranabus thinks it over, then pins his gaze on me. "Look at me directly and tell me you can't find the Kah-Gash."

I don't like him calling me a liar, but I let our eyes meet and say, "I searched for it honestly. I couldn't find it." I hold his gaze, trying not to blink.

Beranabus scowls. "Very well. We'll pick up Cadaver's trail and hope he hasn't laid any more traps for us. Go ahead then, boy. Find him."

"First, you have to promise to help me rescue Art."

"Don't worry," Beranabus huffs. "We'll do all we can to save your little brother. If he's still alive." He spits spitefully. "Which I very much doubt."