He tried to recover his composure. He told himself that the Soviet secret police murdered people, after all, especially anyone suspected of disloyalty. The head of the NKVD, Lavrentiy Beria, was a torturer whose favourite trick was to have his men pull a couple of pretty girls off the street for him to rape as his evening’s entertainment, according to rumour. But the thought that Communists could be as bestial as Nazis was no consolation. One day, he reminded himself, the Soviets would get rid of Beria and his kind, then they could begin to build true Communism. Meanwhile, the priority was to defeat the Nazis.

They came to the canal wall and stood there, watching a barge make its slow progress along the waterway, belching oily black smoke. Volodya mulled over Werner’s alarming confession. ‘What would happen if you stopped investigating these deaths of handicapped children?’ he asked.

‘I’d lose my girlfriend,’ Werner said. ‘She’s as angry about it as I am.’

Volodya was struck by the scary thought that Werner might reveal the truth to his girlfriend. ‘You certainly couldn’t tell her the real reason for your change of mind,’ he said emphatically.

Werner looked stricken, but he did not argue.

Volodya realized that by persuading Werner to abandon his campaign he would be helping the Nazis hide their crimes. He pushed the uncomfortable thought aside. ‘But would you be allowed to keep your job with General Dorn if you promised to drop the matter?’

‘Yes. That’s what they want. But I’m not letting them murder my brother then cover it up. They’ll send me to the front line, but I won’t shut up.’

‘What do you think they’ll do to you when they realize how determined you are?’

‘They’ll throw me in some camp.’

‘And what good will that do?’

‘I just can’t lie down for this.’

Volodya had to get Werner back on side, but so far he had failed to get through. Werner had an answer for everything. He was a smart guy. That was why he was such a valuable spy.

‘What about the others?’ Volodya said.

‘What others?’

‘There must be thousands more handicapped adults and children. Are the Nazis going to kill them all?’

‘Probably.’

‘You certainly won’t be able to stop them if you’re in a prison camp.’

For the first time, Werner did not have a comeback.

Volodya turned away from the water and surveyed the cemetery. A young man in a suit was kneeling at a small tombstone. Was he a tail? Volodya watched carefully. The man was shaking with sobs. He seemed genuine: counter-intelligence agents were not good actors.

‘Look at him,’ Volodya said to Werner.

‘Why?’

‘He’s grieving. Which is what you’re doing.’

‘So what?’

‘Just watch.’

After a minute the man got up, wiped his face with a handkerchief, and walked away.

Volodya said: ‘Now he’s happy. That’s what grieving is about. It doesn’t achieve anything, it just makes you feel better.’

‘You think my asking questions is just to make me feel better.’