‘I . . .’ I tried to think of losing any of them. Of the look on Simon’s mother’s face on learning that her only son was dead. Of the Arnots, if they lost Elton. ‘No! I’m not losing any of them. Tell me how to stop it!’

‘You can’t stop it. It’s the sacrifice. It’s what she costs us. Her life saved. Others lost. One or many? Elton set you the puzzle already. And you ran from it. Ask me again how to stop it and I might tell you. But then you’d have to decide. I could tell you where to find Rust. One word. One word.’

‘I . . .’ Like the spell. One word, and someone who would have lived, dies.

‘Or let it play out. As it already has played out. Let my past be your future. And save Mia.’

‘Mia.’ One short word that sent a hundred vivid images flooding through my mind’s eye. I wanted her. More than anything. More, in that moment, even than I wanted to be well. I stood back, releasing Demus.

He straightened, wincing. He had blood around his mouth. In the light and shadow from the fallen lamp he looked demonic, almost the vampire he had once seemed.

‘I don’t know what you do, Nick. I don’t remember this conversation. I remember the next week. I remember the shit I had to deal with. The bodies that needed to go into the ground. None of this is good. None of it can be. But it happened.’

‘I can’t play this game. I’m sorry.’ I stepped away, bent, and picked up the light. ‘I need to unstick the future, jump us onto another timeline. We all need a chance. I can’t walk your path. I’m sorry.’ I glanced down the dark corridor. ‘Your Mia is old. Forty. She’s lived a life . . .’

Demus bowed his head. ‘How easily the young sacrifice the old. When you get to forty, it won’t seem quite so clear-cut. Believe me. But . . . Well, just remember that you told me the old were a price worth paying.’

‘I didn’t say that.’ Not exactly. Though I kind of had.

Demus pulled back his right sleeve. ‘I don’t have a scar here.’ He drew a finger across the back of his wrist.

‘What?’ I wondered if he had gone mad or was just trying to distract me while Rust killed my friends.

‘I don’t have a scar here.’ He shrugged. ‘If you did . . . then you couldn’t be me. Could you?’ He covered his wrist with his sleeve again. ‘I remember that three people die here tonight. Do it your way and maybe it will be more. Maybe fewer.’ He met my gaze, narrowing his eyes against the light. ‘It’s in your pocket.’

I reached into my coat pocket and there it was, the Stanley knife. I took it out and set the small, razor-sharp blade to the back of my other wrist.

‘Think about it.’ Demus didn’t plead. I was grateful for that.

‘No time.’ And I drew the blade across my skin. I didn’t press hard, but the blood came quickly, along with a sharp, sick-making pain. I turned away, retching. I would have a scar where Demus didn’t. He wasn’t me. His past was no longer my future.

‘Restaurant.’

‘Huh?’ I turned back, wiping acid vomit from my mouth.

‘That’s the killing word. That’s where you’ll find Rust and remake the future.’

John had mentioned a staff restaurant down on the ground floor. I started off. ‘You coming?’

‘Why should I?’ Demus called after me. ‘It’s not my future anymore.’

I reached the corner and looked back. ‘It still matters!’

‘To you maybe.’ His voice came from the dark, further back than my dying torch could show. Silence. Then, just as I was about to go, ‘That was the solution to your other problem, too, you know.’

‘What? What was?’

‘In the Tower of Tricks. Someone had to die. You should have used Power Word Kill on the old man. Everything would have gone away. One old man dead.’

‘Come on!’ And I was running for the stairwell. Only silence followed.

I reached the first floor before nerves started to set in. I was hunting a deranged killer in a darkened building. On my own. Rust had somehow managed to murder and decapitate a well-known local gang leader and then trail us across London carrying the man’s head in a shopping bag. My plan appeared to centre on confronting him with my trusty Stanley knife whose blade, although proven to be sharp, stood less than an inch long.

I leaned out into the corridor from the stairwell and hollered. ‘Elton! Simon!’ I drew breath for another shout when, against all the odds, two lights appeared at the far end of the corridor and came swinging crazily toward me.

‘We got it! We got it!’ Elton was in the lead, holding a flat black box above his head, any concern that too much noise might bring a security guard clearly forgotten.

‘We got it!’ Simon came puffing behind him, red-faced.

‘Got what?’ I glanced around for Rust.

‘The chip, doofus!’ Elton bounced up to me. ‘Si got the combination. I found the safe. A big thing like from World War II, just standing in the corner of an office.’

‘We gotta go. Rust’s here. He’s killed Sacks and I think he’s after Mia.’

‘Rust?’ Elton blinked and took a step back. ‘The lunatic who torched Mia’s place? What’s he doing here?’

‘Murdering people. He followed us. Come on.’ I started down the stairs, feet flying. ‘We have to get the others and go.’

We emerged onto the ground floor, finding it dark and silent.

‘John! Mia!’ I yelled. It had worked before.

Nothing.

‘You guys go that way. I’ll go this way.’ I had spotted a sign to the restaurant.

‘You’re kidding, right?’ Elton grabbed my shoulder. ‘You said he killed Sacks? And you want to split up again?’ He let go and pulled the crowbar from his bag. ‘We take this sucker out together.’

‘John took one half of this floor. Mia took the other. We need to get them both. Go! I got this!’ I waved my little knife as fiercely as I could. Simon and Elton weren’t dying on my watch. I’d get to the restaurant alone.

‘No way—’

A distant cry cut Elton off, coming from the direction I’d tried to send them.

‘Come on!’ And hefting his crowbar he took off, Simon lumbering dutifully behind.

I pretended to run with them, then turned sharply and ran the other way.

The lights were on at the front of the restaurant. I pushed the doors open with shaking hands, trying not to let them squeak. The food counter stood before me, all closed up and covered. Tables and chairs stretched away into the shadows toward darkened windows. A little way ahead of me a figure lay face down in his own blood. A black guy in uniform. A security guard sprawled on the tiles, a gleaming red puddle forming around his side.

Further back into the room something rattled, and I raised the feeble beam of my bicycle lamp.

Rust sat at one of the tables close to the windows, Mia in the chair in front of him. The blade he had was literally a hundred times bigger than mine, a full-sized machete, the bloody cutting edge held within inches of Mia’s neck.

‘Little. Nicky. Hayes.’ Rust put a cigarette in the corner of his mouth. ‘Come to play?’

‘You’re mad.’ I couldn’t help but state the obvious.

Rust shrugged. ‘If I kill all the witnesses, what has anyone got on me but rumours?’ He turned his blade. The blood looked black, like oil. ‘People say I don’t know where to stop. I say, if you never stop, they’ll never catch you.’

Mia stared at me, eyes pleading. I would be doing the same thing in her place. I had no idea what to do. He could cut her throat with a motion and kill me almost as easily. At every moment there were endless worlds branching away from us, worlds where Mia lay dying, worlds where she somehow elbowed him in the face and broke free, and through it all I was stuck in this one, where I stood like an idiot with no plan and less hope. Demus had been right. I could have saved her. He knew she survived. And somehow, by rushing down here to play the hero, I’d let her die.

‘We’ve been waiting for you to show up, Nick.’ Rust kept his voice conversational. ‘I wanted you to see her die.’

‘Don’t. You don’t have to do this!’ I stepped forward.

‘You mistake me.’ Rust moved the blade closer to Mia’s neck. ‘I want to do it.’

‘Just don’t.’ I took another step. Five yards and half a dozen chairs separated us.

‘You’ve got a choice, Nick. You can go back and turn on the main lights so you get a better view. That way, she gets to live sixty seconds longer. Or you can say no, and I’ll do it now.’

‘I . . .’ Movement in the darkness. Someone was advancing from behind them. There must be a back way in. ‘Wait! I’ll do it.’

I started to back toward the light switches by the entrance as slowly as I could.

‘Quicker!’ Rust pressed the flat of the machete blade to Mia’s throat, the cutting edge just beneath her chin. She cried out in terror. ‘Mia’s dying for you to see her better.’

Chairs squealed across the floor as I pushed them aside, hoping to cover the sounds of the approach behind them. I reached the switches and set my hand against them. ‘Lower the blade.’

The figure was behind them now, one hand raised and grasping what might have been a fire extinguisher.

‘Really? You’re trying to give me order—’