Kamen closed the door behind him and sat down. He took from his pocket a toy, a tin soldier with a key in its back. He wound up the key and placed the toy on Volodya’s desk. The soldier swung his arms as if marching, and the clockwork mechanism made a loud ratcheting sound as it wound down.

In a lowered voice Kamen said: ‘Stalin has not been seen for two days.’

Volodya realized that the clockwork soldier was there to swamp any listening device that might be hidden in his office.

He said: ‘What do you mean, he hasn’t been seen?’

‘He has not come to the Kremlin, and he is not answering the phone.’

Volodya was baffled. The leader of a nation could not just disappear. ‘What’s he doing?’

‘No one knows.’ The soldier ran down. Kamen wound it up and set it going again. ‘On Saturday night, when he heard that the Soviet Western Army Group had been encircled by the Germans, he said: “Everything’s lost. I give up. Lenin founded our state and we’ve fucked it up.” Then he went to Kuntsevo.’ Stalin had a country house near the town of Kuntsevo on the outskirts of Moscow. ‘Yesterday he didn’t show up at the Kremlin at his usual time of midday. When they phoned Kuntsevo, no one answered. Today, the same.’

Volodya leaned forward. ‘Is he suffering . . .’ his voice fell to a whisper, ‘a mental breakdown?’

Kamen made a helpless gesture. ‘It wouldn’t be surprising. He insisted, against all the evidence, that Germany would not attack us this year, and now look.’

Volodya nodded. It made sense. Stalin had allowed himself to be officially called Father, Teacher, Great Leader, Transformer of Nature, Great Helmsman, Genius of Mankind, the Greatest Genius of All Times and Peoples. But now it had been proved, even to him, that he had been wrong and everyone else right. Men committed suicide in such circumstances.

The crisis was even worse than Volodya had thought. Not only was the Soviet Union under attack and losing. It was also leaderless. This had to be its most perilous moment since the revolution.

But was it also an opportunity? Could it be a chance to get rid of Stalin?

The last time Stalin had appeared vulnerable was in 1924, when Lenin’s Testament had said that Stalin was not fit to hold power. Since Stalin had survived that crisis his power had seemed unassailable, even – Volodya could now see clearly – when his decisions had verged on madness: the purges, the blunders in Spain, the appointment of the sadist Beria as head of the secret police, the pact with Hitler. Was this emergency the occasion, at last, to break his hold?

Volodya hid his excitement from Kamen and everyone else. He hugged his thoughts to himself as he rode the bus home through the soft light of a summer evening. His journey was delayed by a slow-moving convoy of lorries towing anti-aircraft guns – presumably being deployed by his father, who was in charge of Moscow’s air raid defences.