At some point, I must have fallen asleep. All my dreams were golden. I stood on a mountain bathed in hot sunlight that turned the grass, the rocks, the hills and valleys gold. A golden cross stood behind me. Then I looked down and saw two snakes slithering through the grass towards me. I cried out – but instead of attacking me the snakes turned on each other. One devoured the other, then chased himself, slithering in a circle until he blurred into a haze. He fastened his jaws around his tail and began swallowing himself whole.

I looked again and saw that the snake had become a golden ring. I picked it up; I put it on my head as a crown, and the moment I did so I felt a shaft of golden light well through me like a fountain, connecting the mountain at my feet with the heavens in perfect oneness. An angel with a trumpet appeared in the likeness of my father. He touched my forehead, and the seal of the prophets was set on my brow in gold. I fell to my knees and embraced the golden earth, which was soft and warm and infinitely forgiving.

I woke from my dream. To my horror and delight, I found that Pieter’s outstretched arm had drifted across my waist, his hand cupped between my legs. I had been rubbing myself against him in my sleep. A golden pleasure suffused my body.

Alas, the demons who possess us know our weaknesses and bide their time. My dreams had intoxicated me: I knew I should stop but could not. Whether the same demon had possessed Pieter, or whether he was too sleepfast to recognise what he did, he responded willingly, even eagerly. I kissed him all over his body; I ran my fingers through his golden hair and pressed his face against my chest; I kneaded his soft skin until he gasped. He rolled me onto my side and pressed himself against me, kissing the nape of my neck. We fitted together like two spoons in a drawer. My whole body shuddered with desire and my blood flowed hot like molten gold.

With a crash of thunder, the attic door flew open. The gold in my veins turned to lead. Konrad Schmidt stood on the stair outside, a lantern in his hand and his face slack with bewilderment. I do not know what he expected to find, but surely not his naked son tangled with his apprentice in the most wanton abomination imaginable.

Confusion turned to fury. He stepped into the room, touching the place on his waist where his knife should have been. The attic was narrow and confined; there was no way past him to the door.

I took a final, longing look at Pieter, cowering naked on the bed and screaming it was not his fault. Then I leaped out of the window.

XIII

New York City

For five or ten seconds Nick didn’t remember. He lay between the stiff hotel sheets feeling warm and dislocated, drifting between worlds. The rain had gone; sunlight shone through the white curtains.

Then it came back to him, and he knew the world would never be the same. He rolled over and buried his head in the pillow, as if he could smother the thoughts that overwhelmed him. He sobbed; he tossed and thrashed under the sheets like a drowning man. Images repeated themselves in his mind: Gillian, Bret, the killer chasing him up an endless flight of stairs. He felt broken.

The ring of his cellphone cut through his grief. He groaned and ignored it, wishing it away. It persisted.

He reached out and scrabbled on the bedside table. ‘Nick?’

A woman’s voice. British. Did he recognise it? ‘It’s Emily Sutherland.’ She waited. ‘From the Cloisters?’

‘Right, yes.’ There was some part of Nick that could still function. ‘Listen, it’s not really-’

‘I did some research on that card you brought me. It’s… intriguing.’

‘OK.’

‘Can I meet you to talk about it?’

‘Can you tell me now?’

She hesitated. ‘I – It would be easier in person. It raises some interesting questions. I need to be at the Metropolitan Museum this afternoon. Can you meet me on the roof terrace there?’

‘Sure.’ Anything to get her off the phone.

‘I’ll be there at four.’

He mumbled a goodbye and hung up. He still had the phone in his hand when it rang again. He dragged it back to his ear. ‘Yes?’

‘How you doing this morning?’ It was Royce, a voice from his nightmares. He carried on without waiting for an answer, ‘We need you to come down to the precinct to give us a statement about last night?’

Another wave of tiredness hit Nick. ‘What time is it now?’

‘Twenty after nine. Come as soon as you can.’

The police station on Tenth Street was a squat block that must have been modern once, flanked by two grey towers. Nick was expected. A uniformed officer led him from the lobby through a beige labyrinth of corridors to a small room somewhere deep in the building. There were no windows, only a wide linoleum-framed mirror across one wall. Nick glimpsed his reflection in it and winced. He was still wearing his clothes from yesterday. Something he’d lain in on the rooftop had left an oily smear all across the front of his shirt. A thin itch of stubble dishevelled his cheeks. His eyes were baggy, his hair limp despite the best efforts of the hotel shampoo. His heart sank when he saw a video camera poised on its tripod to record him.

Royce kept him waiting for a quarter of an hour. The moment he entered the room Nick felt himself wilt. Royce was a vampire, feeding off other people’s energy. He flopped into the chair across the table from Nick and leaned forward on sharp elbows.

‘Thanks for coming in. I know it’s a tough time for you.’ He pushed his chair away and leaned back, crossing his legs. He drummed his fingers on the side of his shoe while the technician fiddled with the camera.

‘OK.’ Underneath the lens, a dark red light blinked at Nick. ‘Let’s go. Could you state your name and occupation for the record.’

‘Nick Ash. I work in digital forensic reconstruction.’

Like most people, Royce looked blank. ‘What’s that?’

‘It’s trying to piece together documents that have been torn or shredded beyond recognition. I work on systems that scan the pieces and then digitally reconstruct them using algorithms. The idea is they might be used as evidence.’

‘Do you do that for us?’

‘For the federal government – the FBI, other agencies.’ Again, it sounded good when he wanted to impress someone. For Royce, it was just another opening.

‘Do you have access to classified documents?’

Nick shook his head. ‘It’s still a research programme. The technology’s unproven.’

Royce lost interest. ‘Let’s get to last night. First of all, please describe your relationship with the deceased.’

Nick told them everything he could, starting from when they’d moved in to the apartment. The message from Gillian, the panicked call from Bret, his decision to check on the webcam and what he’d seen. His pulse rose as he described the chase up the stairs, the panicked moments on the rooftop when he thought he’d die.

Royce listened to it all folded up on his chair like a bat. Unlike the night before, there were no interruptions. If anything, Nick found the silence more unsettling. No noise penetrated the room; all he could hear was his own voice and the whine of the video camera.

He finished and looked up. Royce seemed to be examining some blemish on the corner of the table.

‘That’s quite a story.’

What did that mean?

‘Would you say you were close to your room-mate?’

‘We’re – we were – very different people. We got on OK.’

‘The lab had a look at the PC we recovered from your apartment. Couldn’t find much because apparently half your hard drive’s encrypted.’

‘I told you; I work under contract to the FBI.’

‘While your friend’s machine,’ Royce continued, ‘that really opened our eyes. Would it surprise you to hear he had a significant number of indecent images – really, a lot – stored on his computer?’