After a couple of hours, he spotted a peregrine swoop across from a building on Dover Street to the vantage point on one of the Gothic pylons of the bridge. It might even have been nesting there on the makeshift cliff face.

Harper focused on the bird, its head making rapid movements left to right, its dark glossy eye alert, its body holding an imperious pose. The peregrine — known as The Wanderer.

There were no other birds in flight — the presence of the falcon had scared them all away. The falcon was the supreme predator. It could dive at speeds no other animal could reach — up to 240 m.p.h. had been clocked by a diving falcon. The impact of those claws at that speed, taking out a pigeon mid-flight, was something to behold.

Harper’s cell phone vibrated. He pulled it out quickly, thinking it might be Denise Levene. It wasn’t. He put the cell to his ear. ‘What is it?’

‘Man,’ said Eddie Kasper, ‘you really got to work on that phone etiquette.’

‘I’ve got a Ballistics report to pick up.’

‘I got something.’

‘What is it?’ Harper repeated.

‘You ask nicely and I might tell you.’

‘Sorry, I’m outta polite.’

‘You’re your own special category of impolite, Harps.’

Harper put his binoculars to his eyes as the falcon rustled its feathers, flexed its wing muscles and pushed off from the pylon. It was a magical sight, watching it climb higher and higher above the river.

‘You found us a new body?’

‘I didn’t say it’s a homicide,’ said Eddie.

‘I don’t get any other kind of calls, Eddie.’

The falcon rose higher with an effortless beat of its wings, its head scanning the air below, looking for prey.

‘I got wind of a homicide down in South Manhattan with some similarities to our case. I thought you might want to hustle your way in.’

‘What are the connections?’

‘Female. Single gunshot wound. Name’s Marisa Cohen.’

‘She’s Jewish?’

‘She’s called Cohen.’

‘It’s not Lukanov.’

‘Or it’s not only Lukanov,’ said Eddie.

Harper picked up the falcon riding a thermal, silent, with wings outstretched. He felt the hairs on the back of his neck rise and his fingertips tingle. His case had jumped back to life.

‘This is escalating way too quickly. I’m at the Brooklyn Bridge,’ he said. ‘Get right over here, Eddie.’

Harper put his phone back in his jacket and looked up at the sky. The falcon was focused. It had seen its prey.

In Lower Manhattan, Eddie and Harper drove up to Downing Park where the body had been found. South Manhattan Homicide was already on the scene in numbers. Harper got out of the car and looked at Eddie.

It was getting gloomy. The two detectives squinted into the bright lights of the crime scene. Another body meant that Lukanov wasn’t the killer or that there was more than one.

Harper walked across. The crime scene was next to the park, in the courtyard of a haulage company working right on the river. Up above, they could see traffic all the way along FDR to the Brooklyn Bridge and beyond.

‘This road never gets quiet, not even at four a.m.,’ said Harper.

‘What’s your point?’

‘The point is, if this is the killer, it’s something I didn’t consider from the first kill. He might get excited by the idea of getting caught, so he commits crimes close to where people can see. Esther and David were both murdered in public places. He might like the risk. I think he might get off on it.’

‘I don’t know what you got in that head; all I see is the world’s dullest haulage lot.’

Harper walked over to the entrance to the haulage park. He signed them both in on the crime-scene log and wandered to the edge of the platform. There weren’t any boats tied to it. Maybe they didn’t use this place any more. The water was sparkling in the dark. Ink black and flecked with gold.

Harper found Detective Johnny Selinas walking the perimeter, kicking up dust as he shuffled his feet across the ground. Harper shook his hand. Selinas was a veteran. Twenty years in Manhattan South, in which time he’d expanded from 150 lbs to 300 lbs.

‘What you doing here, Harper? Don’t you get a nosebleed if you come this far south?’

‘I try to avoid it, but I think we’ve got something for you.’

‘What’s that?’

‘We’re investigating the David Capske murder uptown. Gunshot to the head, Jewish victim. Thought I’d check out any similarities. Let you know what we have.’

Selinas led Harper over to the body. ‘I don’t know what this is, Harper. Her name is Marisa Cohen, if her purse is hers. She’s been in the river a day maybe. Can’t tell much about the COD. Maybe she drowned, maybe she was strangled and thrown in. Who knows, but she’s also got a gunshot wound right on the crown of the head.’

Harper looked down over the edge of the wooden platform into the water. Her body was hanging about a meter and a half below the platform. Both hands were tethered to the upright wooden stanchion. The wrists were bruised and the flesh torn, the wounds black against her white skin.

‘What else have you got?’ he asked.

‘Nothing yet. It’s early days.’

‘She married?’

‘Yeah. But separated. He’s with someone new, they were together.’

‘You have suspicions?’

‘Wife found bound and drowned, and the husband off with his new mistress? Who knows?’

Harper got down flat and peered at her head wound. It was difficult to tell through the matted hair, but it was a neat little hole. Close range.

‘When do they think they can get her out?’

‘Two boats are on their way. Coroner’s also coming. Couple of hours.’

‘The Capske killer liked to look down on his victim,’ said Harper. ‘Shot him through the forehead from above.’

‘What else you got for me?’ Selinas said.

‘Look for dirt under her fingernails. If it’s boot polish then we might have a match.’

‘What’s your theory?’ Selinas wanted to know.

Harper looked at her hands. It looked like she had the same black dirt under her nails. ‘Someone likes to torture his victims. He likes to draw it out. He goes through some ritual with boot polish. We guess he makes them kneel and clean his boots. There’s writing too. Our guy had the word Loyalty written on a card that was left on his chest, and some unreadable scratches that looked like a homemade tattoo. Put it all together and you’ve got some sociopath with a lot of hatred in his blood. It might be linked to a series of neo-Nazi assaults. Check if she reported any hate crimes.’

‘Marisa Cohen fits most of your killer’s MO,’ said Selinas.

‘Look at her hands,’ said Harper. ‘She’s been tethered. I don’t think it’s to prevent the body floating away. I don’t think he cares about the body once it’s dead. As if it’s meaningless then, like a piece of garbage.’

‘Then why tie her there?’

‘She’s hanging there, isn’t she, with her head just out of the water. He didn’t want her to drown. In fact, he’s tried to prevent it. She’s tried to struggle. Why?’

‘To get away?’

‘Look at the rope marks. She’s tried to pull downwards. That would take her closer to the water.’

‘What for? To escape?’

‘No, I think it was because she wanted to die. She wanted to drown. Because he was keeping her alive for as long as he could.’

‘Sick bastard. Why?’ said Selinas.

‘Because that’s his thing. That’s what excites this maniac.’

The two men let the thought dwell in their minds for a moment.

‘When did you get to the body?’ asked Eddie.

‘We had a team here yesterday afternoon in the area but we didn’t find her until this afternoon.’

‘Why were you searching? Someone call it in?’

‘She called a friend just before she disappeared. The friend missed the call, but she listened to the voicemail and then called the cops. We got another call from some building by the park. They heard screaming.’

‘So what, patrol searched the area?’