‘That experience convinced me that democratic socialism doesn’t work,’ Frunze said. ‘Against the Nazis we were completely impotent. It took the Soviet Union to stop them.’

That was true, and Volodya was pleased Frunze realized it; but, more importantly, the comment showed that Frunze’s political ideas had not been softened by life in affluent America.

Alice said: ‘We were planning to have a couple of drinks at a bar around the corner. A lot of the scientists go there on a Friday night. Would you like to join us?’

The last thing Volodya wanted was to be seen in public with the Frunzes. ‘I don’t know,’ he said. In fact he had been too long with them in this restaurant. It was time for step three: reminding Frunze of his terrible guilt. He leaned forward and lowered his voice. ‘Willi, did you know the Americans were going to drop nuclear bombs on Japan?’

There was a long pause. Volodya held his breath. He was gambling that Frunze would be wracked by remorse.

For a moment he feared he had gone too far. Frunze looked as if he might burst into tears.

Then the scientist took a deep breath and got control of himself. ‘No, I didn’t know,’ he said. ‘None of us did.’

Alice interjected angrily: ‘We assumed the American military would give some demonstration of the power of the bomb, as a threat to make the Japanese surrender earlier.’ So she had known about the bomb beforehand, Volodya noted. He was not surprised. Men found it hard to keep such things from their wives. ‘So we expected a detonation some time, somewhere,’ she went on. ‘But we imagined they would destroy an uninhabited island, or maybe a military facility with a lot of weapons and very few people.’

‘That might have been justifiable,’ Frunze said. ‘But . . .’ His voice fell to a whisper. ‘Nobody thought they would drop it on a city and kill eighty thousand men, women and children.’

Volodya nodded. ‘I thought you might feel this way.’ He had been hoping for it with all his heart.

Frunze said: ‘Who wouldn’t?’

‘Let me ask you an even more important question.’ This was step four. ‘Will they do it again?’

‘I don’t know,’ Frunze said. ‘They might. Christ forgive us all, they might.’

Volodya concealed his satisfaction. He had made Frunze feel responsible for future use of nuclear weapons, as well as past.

Volodya nodded. ‘That’s what we think.’

Alice said sharply: ‘Who’s we?’

She was shrewd, and probably more worldly-wise than her husband. She would be hard to fool, and Volodya decided not to try. He had to risk levelling with her. ‘A fair question,’ he said. ‘And I didn’t come all this way to deceive an old friend. I’m a major in Red Army Intelligence.’

They stared at him. The possibility must have crossed their minds already, but they were surprised by the stark admission.

‘I have something I need to say to you,’ Volodya went on. ‘Something hugely important. Is there somewhere we can go to talk privately?’