Anna stepped forward and to the side, her movements hampered by her bound hands. She took time to aim carefully and swung her foot in a vicious kick onto MacSwain’s temple. He was thrown sideways by the force and smashed into the small galley. He groaned and lay still. Anna ran towards the hatch and slammed her shoulder against it. It didn’t budge. She remembered that it was a sliding hatch and she wriggled her arms and wrists down and below her bottom. Squatting first and then sitting, she slipped her hands behind her knees and looped them over her feet. She cast a sideways glance at MacSwain. He groaned again. Anna scrabbled with her still-bound hands to slide the hatch door open. She was going to make it. Out and over the side. Her chances would be better in the water than half doped and trapped in a boat with a psycho.

The hatch door jammed. Anna summoned up every remaining reserve of strength and will and wrenched at it. It slid open and slammed against its housing. The cool, oil-tainted smell of the river flooded the cabin. Anna lunged upwards towards the night.

There was an animal scream behind her. She felt MacSwain’s full weight crash into her. Her face smashed down hard onto the top step that led to the hatch. The thick iron taste of blood filled her nose and mouth. MacSwain seized a fistful of hair and snapped Anna’s head back hard and pulled her back into the cabin. His fist came down hard against her neck; but Anna realised it wasn’t a punch. She felt the cold metal in her neck and the hard sting of a hypodermic needle. Then the night she had so desperately reached for reached back to her and claimed her.

Saturday 21 June, 10.15 p.m. The Elbe, between Hamburg and Cuxhaven.

Franz Kassel watched the cruiser stop. It was out of the main navigation channels and properly lit-up, unlike the WS25 that had stealthed along behind it. He watched the tall young man emerge on deck. Kassel could not be sure, in the dark and at such a distance, but, when the young man wiped his face with a towel, he could have sworn the towel was stained black. As if with blood. He snapped the binoculars from his eyes and turned to Gebhard.

‘Try to reach Oberkommissarin Klee again. And if you don’t get hold of her, I’m going to pull chummy over just for the hell of it.’

He looked back to the cruiser. There was a plume of foam, white against the black silk of the river.

‘He’s moving …’

Saturday 21 June, 10.25 p.m. Harvestehude, Hamburg.

The white tiled walls of MacSwain’s bathroom glittered antiseptically and the expensive taps and drying rails had a sharp, cold, scalpel gleam. Fabel, Maria and Werner stared at the shape of a man. A dark blue and red diver’s drysuit hung from the shower rail, dripping onto the bright enamel. It had the unnerving appearance of a cast skin. Something that had been sloughed off after a transition. A dive hood was draped over the bath’s rim.