Dervish lays Meera on one of the mansion's many beds. He examines her again, in more detail this time. He tries to wake her by calling her name and gently shaking her. When that fails he goes to the bathroom, comes back with a glass of water, uses his fingers to flick drops at her face. She doesn't stir.

Dervish steps away grimly. "I could try to bring her round with magic," he says, "but I'm not sure how serious the damage is. I could make it worse."

"Why don't you just leave her?" I ask. "She'll live, won't she?"

"I think so."

"Then let her sleep. That'll be best for her, right?"

Dervish stares at me, troubled, then walks out of the room without saying anything. I wrap a blanket over Meera, then close the door on her and head up to the study.

After the dark of the cellar, the study seems warmer and brighter than ever. I lose myself in a large leather chair, knees drawn up to my chest, head tucked between them, weary and afraid. Dervish is standing by a chess set. This is his favourite set, the pieces based on characters from The Lord of the Rings. Dervish picks up a brightly painted hobbit figurine and toys with it absently while he speaks.

"I don't think you've ever truly appreciated the complexities of chess," he says. "So few pieces, yet so many possibilities. No two games are ever the same. You can learn the rules in an afternoon, yet spend the rest of your life trying to master them."

"Stick chess up your ass!" I shout, coming alive with fury. "Bill-E's chained up in the cellar, twisted and insane. Meera's unconscious, maybe comatose. And all you can warble on about - "

"Lord Loss plays chess," Dervish interrupts quietly. "The Demonata are not, by nature, playful creatures, but he's an exception. I don't know where or when he acquired his hunger for the game, but by the time Bartholomew Garadex met him, he was a committed player, albeit one of limited experience."

"Where's this going?" I grumble, though I have an idea.

"When you walked in on your parents, did you notice any chess boards?"

Breathing thinly. Thinking back. The blood. Web-like walls. The demons. And, on the floor, scattered chess pieces, broken boards. Plus the gouged board in the study.

"Yes," I sigh.

Dervish talks swiftly. "Bartholomew played many games with Lord Loss while trying to persuade him to help lift the curse. His familiars weren't allowed to pester Bartholomew at the chess board, so it was the safest way to conduct a conversation with Lord Loss. Over time he noticed that Lord Loss cared almost as much about chess as he did about feeding on humanity's sorrow.

"On a hunch, old Bart severed connections with the demon master and avoided him for several months. When he finally crossed the divide to the Demonata's universe again, Lord Loss was surly and irritable, eager to resume play.

"Bartholomew refused." Dervish chuckles drily. "It's dangerous, riling a demon. They can be abominable angels of destruction when offended. Lord Loss could have unleashed all of his familiars upon old Bart, which would have been - "

"He has others as well as Artery and Vein?" I snap.

"Oh yes," Dervish says. "They're just his current favourites. He has hundreds of familiars. If he'd sicced them on Bartholomew, they'd have torn him limb from limb, and all the magic in the world couldn't have repelled them.

"But, as old Bart had gambled, Lord Loss didn't send the demons in. As intense as his anger was, his fascination with chess proved stronger. Instead of crushing Bartholomew, he whined and complained and tried to bargain. So Bartholomew struck for gold. He told Lord Loss he wouldn't play unless the demon master lifted the curse of the Garadexes.

"No bite. Chess was an obsession, but it wasn't that precious to him. So old Bart tried another approach. He proposed a series of contests in which he'd play for the lives of individual family members. After lengthy discussions, they agreed to stage a number of matches, best of five games per match. For each match that Bartholomew won, Lord Loss would cure a Garadex. But if Bartholomew ever lost, Lord Loss would take possession of his soul.

"And so the contests commenced, two or three games per week - Lord Loss set the rate. According to Bartholomew's records, Lord Loss hated losing. Like most of the Demonata, he's despisingly proud. They consider themselves superior to humans, and to lose to one - at anything -  is a great disgrace.

"Yet lose he did." Dervish chuckles throatily. "Bartholomew gave his time over entirely to chess, playing for hours on end each day and night, with the best opponents he could find, learning and improving. He lost six games in the first three months - then never again. He hit a fifty-nine game winning streak, which showed no sign of ending.

"And then he died."

Dervish shrugs. "He was old, and his earlier battles with Lord Loss's familiars had drained him. It was peaceful in the end - he passed away in his sleep."

"What happened then?" I ask, absorbed in the story.

"For a long time, nothing," Dervish says. "Nobody in our family knew of Bartholomew's matches with Lord Loss. He never told them how he was affecting the cures. Several Garadexes were witches and wizards, but they were unable to unlock the secrets of his diaries, which he'd encoded with strong spells.

"Eventually, almost forty years after the great magician's death, Davey McKay - a distant relative who'd lost four of his five children to the curse decoded the diary and discovered the demonic secret. He immediately contacted Lord Loss in an attempt to renew the contests and reverse the change in his youngest child, who was just starting to transform.

"The demon master was slow to respond. Bartholomew had humiliated him. He was wary of suffering another string of defeats at the hands of a human. Also, Davey wasn't a magician - his soul was of only minor interest to Lord Loss. But Davey was resourceful. He sought a twist to spike Lord Loss's imagination, a challenge which would appeal to his warped sensibilities."

Dervish lapses into a thoughtful silence. He's still playing with the hobbit chess piece. With his free hand, he pulls open a drawer and takes out a photo. Slides it across the desk. I look - Mum, Dad, Gret and me. A snap taken on one of Dad's birthdays.

"Davey's solution was dreadful," Dervish says as I stare at the photo, "but it had to be. Lord Loss wasn't interested in anything less. The rules he proposed were - one match, best of five games, like before. If Davey won, his son would have his humanity restored, and both would be free. But if Lord Loss won, he could kill both Davey and the child.

"Lord Loss was keen on Davey's idea, but he added a few kinks of his own. When playing Bartholomew, he'd told his familiars to stand at bay. He refused to grant Davey that privilege. Somebody would have to partner Davey and fight the demons while he played. As long as Davey's protector lived, the familiars wouldn't attack Davey. But if his partner was killed they'd be free to slaughter Davey and his son too.

"Another new rule was that the games had to be played simultaneously, in a single sitting - to heap the pressure on Davey and his partner. And his final clause - if Davey won, he'd have to enter Lord Loss's realm and fight him personally for possession of his soul."

"What?" I mutter, not catching the meaning of the last part.

"The games take place between the Demonata's universe and ours," Dervish explains. "You probably noticed in your parents' room that there were bits of our world as well as bits of Lord Loss's. That in-between state was where Davey would challenge Lord Loss. If Davey won, his son would be cured, and the boy and Davey's partner could get on with their lives. But Davey would have to enter Lord Loss's world and fight the demon master on his home turf. If he beat him, he'd walk free. But if he lost, Lord Loss would take control of his soul, and he'd live out his remaining days as a zombie."

"Sounds like a raw deal to me," I grunt.

"It was," Dervish agrees. "But those were the terms. Davey had to agree." Dervish pauses, then says softly, "Davey lost. His brother stood as his partner. The demons overwhelmed him. Davey was killed before even one of the games was decided. His son too. All three were ripped to pieces by the demons."

He takes the photo from me and gazes at it in heavy silence.

"But Davey's sacrifice wasn't in vain," he resumes. "Lord Loss developed a taste for this new contest. He approached Davey's relatives - those with magical powers - offering them the chance to compete for lives as Davey had.

"Most refused. But two - both with young children on the verge of turning - accepted the challenge. One was defeated - but the other won. His victory gave hope to others, and a series of Garadexes and Gradys have sustained the challenge over the long decades since. Some win, some lose. Most who win subsequently lose their souls in the ensuing battle in Lord Loss's realm, but a few have made the journey back, proof that it can be done."

Dervish lays the photo back in the drawer and closes it slowly. He blinks owlishly and wipes a hand across his eyes - he's fighting back tears.

"Your parents didn't win," he says. "Gret was infected. Your father and mother challenged Lord Loss. One of them proved inadequate to the task. All three died as a result. I was meant - "

His voice catches and he turns away, rubbing his eyelids, trembling with emotion. "Your father and I had an agreement," he says bleakly. "If any of his children succumbed to the disease, I was to be his partner. I thought he was wrong to have children, but I loved him, and I loved the kids he fathered. I wasn't going to stand to one side in their hour of need."

"Then why weren't you there?" I cry, tears streaming down my cheeks.

"He never told me Gret was changing," he croaks. "Your mother must have convinced him to let her face the demons with him. I'm sure Sharon had Gret's best interests at heart, but I was a better chess player, and a much stronger fighter. Cal should have held me to my promise. He should have called. Maybe I could have..."

He breaks down. His eyes close. His hands clench into fists. Then he raises his face to the ceiling and howls. From the secret cellar I imagine I hear an echoing howl, as the transformed Bill-E Spleen pauses during feeding and answers his uncle's tortured call.

I stop crying before Dervish does. I don't think he cries very often, so he has a hard time regaining control. When the tears finally cease and he's wiping his face clean with a denim sleeve, I put an accusation to him as softly as I can. "Are you saying it was Mum's fault?"

"Of course not!" he answers promptly.

"But if Dad had picked you instead of her..."

Dervish hesitates, choosing his words carefully. "I've got to be truthful - I was the logical choice. But logic and magic don't always mix. Sometimes amateurs fare better than professionals. Nobody ever really knows how they'll fare until they put themselves on the spot."

He pulls out a handkerchief and blows his nose. "In the end, it's all relative. Your father chose -  rightly or wrongly - and the outcome stands. We can't change the past and we'd be fools if we tried.

"But whatever my personal feelings about his choice," Dervish adds, "don't ever think I believe it was your mother's fault. It wasn't. It was our curse, not hers. She deserves nothing short of absolute love and respect for taking on that curse, and laying her life on the line to try and avert it."

I nod slowly, thinking it over. "But if they hadn't laid their lives on the line," I whisper. "If they'd called in the Lambs and not gone to Lord Loss..."

"They'd be alive." Dervish says it bluntly. "That's why I said you might not like the truth. They put Gret's life before their own - and yours. If they hadn't interfered, you'd have lost a sister but kept your parents."

I stare at him uncertainly, my lower lip trembling, part of me hating Mum and Dad for putting me through this, another part hating Gret, blaming her for the mess.

Dervish reads my thoughts and shakes his head calmly. "Don't go down that road, Grubbs," he says. "Cal and Sharon did what they had to. They'd have done the same for you if you'd been infected. I know you feel cheated. I know you want them back. But if you look deep inside, and recall the people they were, the love they had for you and Gret, you'll understand why they did it."

"They should have told me," I moan. "They cut me out completely. I could have helped. I - "

"No," Dervish says firmly. "The rules are clear - only two may challenge Lord Loss and his familiars. Telling you would have achieved nothing."

"It would have prepared me for the worst," I disagree.

"I don't think they wanted to think about that," Dervish sighs. "Doubts have a way of eating a person from the inside out. Most who face Lord Loss choose not to focus on all that can go wrong, because it makes it more likely that something will go wrong."

"But - " I begin.

"Grubbs," Dervish interrupts curtly, "we can sit here arguing all night. But that won't bring your parents and Gret back. And it won't help Billy. Letting go isn't easy, but you have to forget about your parents for a while. If you can't, you're no good to me."

"'No good to you'?" I echo, frowning. "What are you talking about? What do you want me to do?"

Dervish leans forward, his features impassive. "I want you to be my second," he says. "I want you to stand by my side and battle Vein and Artery while I challenge Lord Loss at chess."

The world goes numb.