‘I’ve told your father,’ Zoya went on. ‘He listens to me, but no one listens to him.’

‘So what are you going to do?’

‘What can I do? I’m going to make a damn good bomb sight for our airmen, and hope for the best.’

Volodya nodded. He liked that attitude. He liked this girl. She was smart and feisty and a joy to look at. He wondered if she would go to a movie with him.

Talk of physics reminded him of Willi Frunze, who had been his friend at the Berlin Boys’ Academy. According to Werner Franck, Willi was a brilliant physicist now studying in England. He might know something about the fission bomb Zoya was so exercised about. And if he was still a Communist he might be willing to tell what he knew. Volodya made a mental note to send a cable to the Red Army Intelligence desk in the London embassy.

His parents came in. Father was in full dress uniform, Mother in a coat and hat. They had been to one of the many interminable ceremonies the army loved: Stalin insisted such rituals continue, despite the German invasion, because they were so good for morale.

They cooed over the twins for a few minutes, but Father looked distracted. He muttered something about a phone call and went immediately to his study. Mother began to make supper.

Volodya talked to the three women in the kitchen, but he was desperate to speak to his father. He thought he could guess the subject of Father’s urgent phone call: the overthrow of Stalin was being either planned or prevented right now, probably here in this building.

After a few minutes he decided to risk the old man’s wrath and interrupt him. He excused himself and went to the study. But his father was just coming out. ‘I have to go to Kuntsevo,’ he said.

Volodya longed to know what was going on. ‘Why?’ he said.

Grigori ignored the question. ‘I’ve called down for my car, but my chauffeur has gone home. You can drive me.’

Volodya was thrilled. He had never been to Stalin’s dacha. Now he was going there at a moment of profound crisis.

‘Come on,’ his father said impatiently.

They shouted goodbyes from the hallway and went out.

Grigori’s car was a black ZIS-101A, a Soviet copy of an American Packard, with three-speed automatic transmission. Its top speed was about eighty miles per hour. Volodya got behind the wheel and pulled away.

He drove through the Arbat, a neighbourhood of craftsmen and intellectuals, and out on to the westward Mozhaisk Highway. ‘Have you been summoned by Comrade Stalin?’ he asked his father.

‘No. Stalin has been incommunicado for two days.’

‘That’s what I heard.’

‘Did you? It’s supposed to be secret.’

‘You can’t keep something like that secret. What’s happening now?’

‘A group of us are going to Kuntsevo to see him.’

Volodya asked the key question. ‘For what purpose?’

‘Primarily to find out whether he’s alive or dead.’