She knew he would not remember their first conversation. ‘You were very candid,’ Carla told him in a low voice. There was no one nearby. ‘You said we were losing the war.’

His eyes flashed fear. He was no longer a woozy patient in a hospital gown with stubble on his cheeks. He was washed and shaved, sitting upright in dark-blue pyjamas buttoned to the throat. ‘I suppose you’re going to report me to the Gestapo,’ he said. ‘I don’t think a man should be held to account for what he says when he’s sick and raving.’

‘You weren’t raving,’ she said. ‘You were very clear. But I’m not going to report you to anyone.’

‘No?’

‘Because you are right.’

He was surprised. ‘Now I should report you.’

‘If you do, I’ll say that you insulted Hitler in your delirium, and when I threatened to report it you made up a story about me in self-defence.’

‘If I denounce you, you’ll denounce me,’ he said. ‘Stalemate.’

‘But you’re not going to denounce me,’ she said. ‘I know that, because I know you. I’ve nursed you. You’re a good man. You joined the army for love of your country, but you hate the war and you hate the Nazis.’ She was 99 per cent sure of this.

‘It’s very dangerous to talk like that.’

‘I know.’

‘So this isn’t just a casual conversation.’

‘Correct. You said that millions of people are going to die just because the Nazis are too proud to surrender.’

‘Did I?’

‘You can help save some of those millions.’

‘How?’

Carla paused. This was where she put her life on the line. ‘Any information you have, I can pass it to the appropriate quarters.’ She held her breath. If she was wrong about Beck, she was dead.

She read amazement in his look. He could hardly imagine that this briskly efficient young nurse was a spy. But he believed her, she could see that. He said: ‘I think I understand you.’

She handed him a green hospital file folder, empty.

He took it. ‘What’s this for?’ he said.

‘You’re a soldier, you understand camouflage.’

He nodded. ‘You’re risking your life,’ he said, and she saw something like admiration in his eyes.

‘So are you, now.’

‘Yes,’ said Colonel Beck. ‘But I’m used to it.’

(ii)

Early in the morning, Thomas Macke took young Werner Franck to the Plötzensee Prison in the western suburb of Charlottenburg. ‘You should see this,’ he said. ‘Then you can tell General Dorn how effective we are.’

He parked in the Königsdamm and led Werner to the rear of the main prison. They entered a room twenty-five feet long and about half as wide. Waiting there was a man dressed in a tailcoat, a top hat and white gloves. Werner frowned at the peculiar costume. ‘This is Herr Reichhart,’ said Macke. ‘The executioner.’

Werner swallowed. ‘So we’re going to witness an execution?’

‘Yes.’

With a casual air that might have been faked, Werner said: ‘Why the fancy dress outfit?’