I can't believe it happened. I know it must have - the evidence is splattered all over Lord Loss and his arachnid throne - but still I can't take it in. Nadia can't be dead, not so suddenly, so bloodily. Surely, even this warped universe of horrors can't be that cruel.

While my brain's whirring, Cadaver shrieks and tosses Art at Lord Loss, then makes a break for freedom, racing to a wall which has slightly fewer demons on it, scuttling towards a window.

Lord Loss catches Art smoothly and cradles him to his chest, keeping him clear of the hole where the snakes are slithering over and under each other. Art laughs, undisturbed. Lord Loss whistles to the demons on the wall. They surge round the window, blocking it, driving Cadaver back.

The demon momentarily thinks about fighting then releases his grip and drops to the floor. In a crouch, he lets the hairs on his arms grow to their fullest length, glares at Lord Loss and waits for the demon master to make the next move.

Lord Loss chuckles at Art or Cadaver, I'm not sure which. Then he says something twisted - it must be a demon language. Cadaver falls to the floor, writhing and hissing. He rolls around, scratching at his throat and face. The demons on the walls laugh and screech at him.

Then, over the sounds of the demons comes a strangely mixed cry of fear and delight. Cadaver stops struggling and sits up. The cry comes again, and this time I realise it comes from Cadaver. He's been altered. He has a mouth.

"I have honoured my end of the bargain," Lord Loss says. Cadaver screams unintelligibly in response. "Such language," Lord Loss tuts. "I am glad most of my guests are not able to understand you or their ears would sizzle. I apologise, Beranabus. Such curses should not be uttered even in this universe."

"I've heard worse," Beranabus says. "Usually from demons I'm about to kill." Cadaver goes silent and shifts his attention to Beranabus, eyeing him suspiciously. Beranabus smiles icily. "Don't worry. If you answer my questions honestly - and that should be much easier now you have a mouth - I won't kill you. My advice is to come quietly. Fight if you wish, but without Lord Loss to protect you, we both know you can't win."

Cadaver bristles and looks at Lord Loss. He says something low and pleading. Lord Loss shakes his head. "No. I vowed to give you a mouth and voice, and promised to protect you until that time. I have acted in good faith. I owe you nothing more."

Cadaver sneers, then spits on the floor, putting his new mouth to good use. Facing Beranabus, he retracts his hairs and marches towards him with pride, offering himself to the magician, hateful but resigned. When Cadaver is by his side, Beranabus raises an eyebrow at Lord Loss.

"Go," the demon master says, waving at the demons round the door, who part at his command. He's smiling. His eyes flicker down at Art, then up at me. He knows this isn't over, that there's more miserable pleasure to be had.

Beranabus starts towards the door.

"Wait," I stop him. "What about Art?"

Shark, Sharmila and Dervish haven't moved. They're looking at Beranabus like I am, questioningly, aware of the promise he made.

"There's nothing we can do," Beranabus says without looking back.

"But you said - " I start to protest.

"That was before I knew Lord Loss ordered the theft," Beranabus snaps. "I thought if the child was alive we'd only have to pry him from Cadaver. But he's the demon master's plaything now. He's lost. Accept it."

"Toothy little Art," Lord Loss purrs, tossing him up into the air, grey teeth exposed, red eyes narrow slits. "Do you want to see what happens when I bite, Art?"

"Leave him alone!" I scream. I take a step towards Lord Loss. Stop. Glance back at Beranabus, wanting him to back me up. But he doesn't even turn his head.

As I waver, torn between wanting to save Art and knowing it means death to face Lord Loss by myself, Dervish steps up beside me. "I'm with you," he says quietly, causing my eyes to fill with grateful tears.

"It's madness," Shark says, taking up position on my other side, "but how could I leave a couple of kids behind?"

I smile at the ex-soldier, then look hopefully at Sharmila. She bites her lower lip and stares at Beranabus. He has turned and is studying us expressionlessly. Sharmila hesitates, starts to smile, then shakes her head. "I am sorry," she whispers. "It is hopeless. The first thing we learn as Disciples is not to throw our lives away. We have to choose our battles carefully and only fight those which we can win."

"Coward," Shark growls.

"No," Dervish says. "It's the sensible choice."

Lord Loss is beaming at us, loving this. "Such brave boys," he murmurs, tickling Art's chin, careful not to be bitten.

"I can't let you do this," Beranabus says. "I need you - especially Kernel."

"You were quick enough to offer our lives a minute ago," Shark reminds him.

"But now I have what we came for - Cadaver. I won't leave you to be needlessly slaughtered. I can force you to come with me."

"I only came for Art," I tell him. "There's no point trying to take me. Even if you could, it wouldn't do you any good. I'd never open a window again, unless it was a window back to this place. Try me - see if I'm bluffing."

Beranabus sighs, then squints at Lord Loss. "Can we do a deal for the child?"

"Perhaps," Lord Loss replies smoothly. "But I'm not sure I want to. This is far more interesting. I'm dying to see if you will really abandon them, or if you and Miss Mukherji will also stay and fight."

"There's no chance of that happening," Beranabus says.

"You are certain?"

"Aye."

"Then the pair of you cannot be part of any deal," Lord Loss says, turning his attention to me. He strokes Art's head softly, cooing. Grins, eyes alive with evil. "How much do you love your brother, Cornelius?"

"Not enough to let you murder me for him," I reply, thinking about Nadia.

"You wouldn't give your life to save his?" Lord Loss asks, surprised.

"I'd risk it, but I won't throw it away."

"Interesting." Lord Loss purses his lips. After a few moments he calls, "Vein!"

A dog-shaped demon slithers down one of the walls. It looks like a black labrador with a crocodile's head and a woman's delicate hands instead of paws. She trots over to her master and waits by the foot of the spider-shaped throne.

"The Board," Lord Loss says, and the demon races out of the room.

Silence, waiting for the demon called Vein to return with whatever Lord Loss sent her for. I watch Art play in the demon master's arms, wishing I could be as ignorant of danger as my brother.

While I'm thinking about that, my mind replays all that's been said. Frowning, I ask, "Why did you steal Art?"

"I didn't," Lord Loss says. "Cadaver took him."

"But you told him to. You hired him. Why? Was it to get at me? Did you know about my gift?"

"What gift?" Lord Loss asks.

"Careful," Beranabus warns. "Don't tell him anything about yourself."

"So it wasn't because you wanted me?" I press.

"No," Lord Loss says. "I remembered you from our previous encounter, but - "

"You've met before?" Beranabus barks, startled.

"Cornelius and I are old acquaintances," Lord Loss says. He smiles at me. "I guessed you would come after your brother, but I expected you to perish along the way. You held no interest for me then - although you certainly do now."

"It wasn't a trap?"

"Why go to all that effort to trap a boy I barely know?" Lord Loss laughs. "This gift of yours must be something very special if you think - "

"Kernel!" Beranabus barks.

I wave him quiet, letting him know I'm not stupid, that I'm taking care. "Why?" I ask again. "Why steal Art?"

Lord Loss smiles smugly. "That answer is tied in with the game I plan to let you play -  assuming you're agreeable. Ah, here's Vein. We can begin."

I look around and see the crocodile-dog making for her master with a chess board grasped in her mouth. It's a few inches thick, made of glass or crystal. Beranabus' eyes widen when he sees the board. He starts towards Vein, as though to take the board from her, then stops and squints at Lord Loss. "Is that...?"

"Yes. The Board. The original."

"I thought it was lost forever, deep beneath the earth."

"No. I rescued it."

"I can't play chess," I tell Lord Loss. "I know some of the rules, but not all of them."

"That's all right," Lord Loss says, floating down from his throne, taking the Board from Vein, wiping the surface clear of spit and slime. He looks at the black and white squares, smiling softly. "This is not a regular board. It is the very first chess board, given to humans by ancient beings who came to Earth from the stars. It was designed for greater things than chess, and since unlocking its secrets I no longer play upon it. The Board is better suited to other games. To battle."

"I don't understand," I frown.

Lord Loss sets the Board on the floor. "Size, like time, can be different here. In this universe, an object can be both immense and microscopic. The Board is tiny in form, but enormous within. It contains a variety of universes in which I can place the souls of you and your loyal friends. There is no physical exit. Only the truth can guide you out."

Lord Loss holds up three arms. "You came in search of a demon thief. Since there are three of you, I will give you three chances to find that thief inside the Board, to apprehend and name him. If you do, your brother will be returned to you and you can take him home, if that is your wish. Otherwise you will remain trapped in the Board for the remainder of your life - and that will be a long, slow, horrible life, Cornelius. One of unimaginable darkness and misery."

"No," Beranabus hisses. "You can't ask that of him. He's just a boy."

"Quiet!" Lord Loss bellows. "You had your chance to be a participant. Now be silent, like any other bystander."

I stare at the demon master, confused. "I don't get it. I know who the thief is. I already found him. Cadaver."

Lord Loss shrugs. "If you and your companions agree to this, I will separate your souls from your bodies - a painless process - and secure them within the Board. You must search for the demon thief there, just as you searched for him here. I'll give you three chances to find and name him. There is no time limit, but if you name the wrong thief on three occasions, your souls will remain captive in the Board. You'll live out the rest of your lives there, and those lives will last hundreds, maybe thousands, of years as you experience time."

He stops and waits for my answer.

I'm still not entirely sure about the rules. Why would I name another demon as the thief when I know it's Cadaver? Unless there will be others disguised as Cadaver and I have to separate the real thief from the fakes.

"What do you think?" I ask Dervish and Shark.

"Will we have to fight?" Shark asks Lord Loss.

"Oh, yes," Lord Loss says with relish.

"Can we die?" Dervish frowns. "I mean, if we don't have actual bodies..."

"Although I'll separate your souls from your bodies, you will retain your current forms when you enter the Board," Lord Loss explains. "If you are killed during the game, your makeshift bodies will dissolve and I will gain control of your souls."

Shark shrugs. "I don't quite get all that, but I'm still with you.

"Me too," Dervish says.

I smile at them, then face Lord Loss. "OK. We'll do it. But I want your word that - "

I get no further. Lord Loss barks a quick spell. Webs drop from the ceiling and ensnare us. We start to struggle, but then the webs go up in flames. I feel a stinging sensation. My body seems to melt away. I try to scream. A red veil passes over my eyes. Then the castle, demons and world around me blink out of existence.