But the place stood across the street from the Kreuzberg police station, so it was a cop bar. That meant it was free to break all the rules. Gambling was open, street girls gave blow jobs in the toilet, and the food inspectors of the Berlin city government never entered the kitchen. It opened when Fritz got up and closed when the last drinker went home.

Macke had been a lowly police officer at the Kreuzberg station years ago, before the Nazis took over and men such as he were suddenly given a break. Some of his former colleagues still drank at the Tannenberg, and he could be sure of seeing a familiar face or two. He still liked to talk to old friends, even though he had risen so far above them, becoming an inspector and a member of the SS.

‘You’ve done well, Thomas, I’ll give you that,’ said Bernhardt Engel, who had been a sergeant over Macke in 1932 and was still a sergeant. ‘Good luck to you, son.’ He raised to his lips the stein of beer that Macke had bought him.

‘I won’t argue with you,’ Macke replied. ‘Though I will say, Superintendent Kringelein is a lot worse to work for than you were.’

‘I was too soft on you boys,’ Bernhardt admitted.

Another old comrade, Franz Edel, laughed scornfully. ‘I wouldn’t say soft!’

Glancing out of the window, Macke saw a motorcycle pull up outside driven by a young man in the light-blue belted jacket of an air force officer. He looked familiar: Macke had seen him somewhere before. He had over-long red-blond hair flopping on to a patrician forehead. He crossed the pavement and came into the Tannenberg.

Macke remembered the name. He was Werner Franck, spoiled son of the radio manufacturer Ludi Franck.

Werner came to the bar and asked for a pack of Kamel cigarettes. How predictable, Macke thought, that the playboy should smoke American-style cigarettes, even if they were a German imitation.

Werner paid, opened the pack, took out a cigarette, and asked Fritz for a light. Turning to leave, cigarette in his mouth tilted at a rakish angle, he caught Macke’s eye and, after a moment’s thought, said: ‘Inspector Macke.’

The men in the bar all stared at Macke to see what he would say.

He nodded casually. ‘How are you, young Werner?’

‘Very well, sir, thank you.’

Macke was pleased, but surprised, by the respectful tone. He recalled Werner as an arrogant whippersnapper with insufficient respect for authority.

‘I’m just back from a visit to the Eastern Front with General Dorn,’ Werner added.

Macke sensed the cops in the bar become alert to the conversation. A man who had been to the Eastern Front merited respect. Macke could not help feeling pleased that they were all impressed that he moved in such elevated circles.

Werner offered Macke the cigarette pack, and Macke took one. ‘A beer,’ Werner said to Fritz. Turning back to Macke, he said: ‘May I buy you a drink, Inspector?’