The laden Rhineship ploughed on towards Rotterdam, its glassy bow wave barely altering as the brown river widened, the Nederrijn imperceptibly becoming the Lek, then taking in the broad flow of the Nieuwe Maas. For most of the morning, he’d been blind to the passing scenery. They’d drifted through small, prosperous towns, with their mixture of tall town-houses and squat industrial buildings, church spires stabbing the flat grey skies, but he couldn’t have described a single one of them, save from memory of previous trips. He’d registered neither the grassy dykes that obscured the lengthy stretches of flat countryside nor the graceful sweeps of road and rail bridges that broke up the long reaches of river.

The pictures he kept seeing were very different. The way Pieter de Groot had crumpled to the floor when he’d hit him on the back of his head with the sap he’d made himself, sewing the soft chamois leather with tight stitches then stuffing it with bird-shot. He couldn’t imagine himself ever doing what de Groot had done, trusting a stranger enough to turn his back on him within five minutes of meeting. Anyone that careless of his safety deserved what was coming to him.

More thrilling pictures. The panic in the heartless bastard’s eyes when he’d come round to find himself bound naked to the top of his own desk. Curiously, his terror had subsided when the bargee had spoken. ‘You’re going to die here,’ he’d said. ‘You deserve it. You’ve played at being God. Well, now I’m going to teach you what happens when somebody plays God with you. You’ve fucked up people’s heads for too long, and now it’s your turn to get fucked up. I can make it fast because, believe me, you don’t want it to be slow. But if you scream when I take the gag out of your mouth, I’m going to hurt you so much you’ll be begging to die.’ He’d been surprised by the reaction. His first victim had struggled, refusing to accept it was pointless. That, it seemed to him, was a natural response. It had irritated him, because it had made his work more difficult. But he’d respected it. It was how a man should behave.

The professor in Leiden, though. He’d been different. It was as if he instantly recognized that the person staring down at him was beyond the reach of any argument he could raise against his fate. He’d given up the ghost there and then, his eyes dull with defeat.