She continued to draw him out. ‘And Italy looks bad.’ The Italian dictator Benito Mussolini – Hitler’s greatest ally – had fallen.

‘Remember 1939, and 1940?’ Beck said nostalgically. ‘One brilliant lightning victory after another. Those were the days.’

Clearly he was not ideological, perhaps not even political. He was a normal patriotic soldier who had stopped kidding himself.

Carla led him on. ‘It can’t be true that the army is short of everything from bullets to underpants.’ This kind of mildly risky talk was not unusual in Berlin nowadays.

‘Of course we are.’ Beck was radically disinhibited but quite articulate. ‘Germany simply can’t produce as many guns and tanks as the Soviet Union, Great Britain and the United States combined – especially when we’re being bombed constantly. And no matter how many Russians we kill, the Red Army seems to have an inexhaustible supply of new recruits.’

‘What do you think will happen?’

‘The Nazis will never admit defeat, of course. So more people will die. Millions more, just because they’re too proud to yield. Insanity. Insanity.’ He drifted off to sleep.

You had to be sick – or crazy – to voice such thoughts, but Carla believed that more and more people were thinking that way. Despite relentless government propaganda it was becoming clear that Hitler was losing the war.

There had been no police investigation of the death of Joachim Koch. It had been reported in the newspaper as a road accident. Carla had got over the initial shock, but every now and again the realization hit her that she had killed a man, and she would relive his death in her imagination. It made her shake and she had to sit down. This had happened only once when she was on duty, fortunately, and she had passed that off as a faint due to hunger – highly plausible in wartime Berlin. Her mother was worse. Strange, that Maud had loved Joachim, weak and foolish as he was; but there was no explaining love. Carla herself had completely misjudged Werner Franck, thinking he was strong and brave, only to learn that he was selfish and weak.

She talked to Beck a lot before he was discharged, probing to find out what kind of man he was. Once recovered, he never again spoke indiscreetly about the war. She learned that he was a career soldier, his wife was dead, and his married daughter lived in Buenos Aires. His father had been a Berlin city councillor: he did not say for which party, so clearly it was not the Nazis or any of their allies. He never said anything bad about Hitler, but he never said anything good either, nor did he speak disparagingly of Jews or Communists. These days that in itself was close to insubordination.

His lung would heal, but he would never again be strong enough for active service, and he told her he was being posted to the General Staff. He could become a diamond mine of vital secrets. She would be risking her life if she tried to recruit him – but she had to try.