‘But you didn’t have to be mad to end up in their clutches. If you were deaf or blind, retarded or disabled, you had to be got rid of for the sake of the master race. A stammer or a harelip was enough to see you sent off.’ He paused and sipped cautiously at his beer, his shoulders hunching closer than seemed possible.

‘Me and your granddad, we weren’t mentally or physically handicapped. We weren’t mad. We were just badly behaved lads. Anti-social, they called us. I was always up to mischief. I’d never do what my mother told me. My dad was dead, and she wasn’t much good at keeping me in order. So I was running wild. Stealing, throwing stones, making fun of the soldiers goose-stepping through the town.’ He shook his head. ‘I was only eight years old. I didn’t know any better.

‘Anyway, one morning a doctor arrived at the house with a couple of men in white coats and SS boots. I fought like a tiger, but they just beat the living shit out of me and threw me into the back of what had been an ambulance. Now, it was more like a police van. They chained me to the wall and we set off. By the end of the day, there were a dozen of us in there, scared out of our wits, sitting in our own piss and shit. Your granddad was one of them. We were sitting next to each other, and that was the beginning of our friendship. I reckon that’s how we survived. We managed to keep some sort of human contact alive between us, in spite of everything that happened.’ Holtz finally met the barge skipper’s eyes. ‘That’s the hardest thing. Remembering you’re human.’

‘Where did they take you?’ the skipper inquired. He knew it was probably the least important thing he could ask, but he sensed already that Holtz’s story would be far from pretty. Anything that would derail or even delay it seemed like a good idea.

‘Schloss Hochenstein. I’ll never forget my first sight of it. You only had to look at it to feel the fear rising up and choking you. A great big castle, like something out of a horror film. Inside, it was always dark, always cold. Stone floors, tiny high windows and walls that seemed to sweat damp. You’d lie shivering in your bed at night, wondering if you’d still be alive in the morning. You never cried, though. If you made a fuss, you got injections. And if you got injections, you died. It was like living in a nightmare you can’t wake up from.