He took his coat and hat from the housekeeper and stopped by his study to pick up his briefcase. At five to eight, he opened the front door, where his driver was waiting. The two men exchanged Heil Hitlers, one with considerably more enthusiasm than the other.

Ferdinand Rudolf von Buhler settled into the back of his Horch for the twenty-minute drive to the embassy. It was going to be a trying week, even more so than usual. Tomorrow was Hitler’s birthday, an event marked with a good deal of extravagance at the embassy. It was bad enough being required to indulge in this enthusiasm, but worse was the expectation that Danes would share it. Of his many Danish contacts, only two had no other engagements for that evening. German officers would have to be drafted in to ensure the reception had a respectable turnout.

But Ferdinand Rudolf von Buhler was about to find out that Hitler’s birthday celebrations would be the least of his problems that week. The first sign of trouble came as the Horch entered Nørrebro. They were on the main road, which had been carefully selected because it was so busy in the morning that cars were obliged to drive slowly.

As he always did, von Buhler watched carefully as they drove past the pharmacy, a beautiful building with a Beaux Arts facade in pinkish-red brick. On a shelf high in the window were three enormous blue medicine jars. Except this morning the three blue jars had been joined by one red one. The message was clear and caused the commercial attaché of the German Embassy to Denmark to experience a sensation of fear and excitement.

‘Georg, I’ve just realised I’m short of cigarettes. Stop at the tobacconist’s, please.’

‘The usual one, sir?’

‘Of course, Georg.’

The tobacconist’s was more a kiosk than a shop, so narrow there was room for only one customer inside it at a time, which von Buhler imagined was the reason it had been chosen for this purpose.

‘Two packets of ten, please.’

The tobacconist took two packets from the shelf behind him. ‘And I imagine you’d like matches today, sir?’

The message was confirmed. He was needed: urgently.

Before Ferdinand Rudolf von Buhler had even removed his coat in his office on the fifth floor of the German Embassy, he checked his appointments for the day with his secretary.

‘There’s the routine with the ambassador at ten, and at eleven you have the Dairy Industry Federation coming in. That is scheduled to finish by a quarter to one, and then your driver will take you to lunch, which is with Herr Lorenz of the shipping agency at the fish restaurant on Nyhavn.’

‘Cancel that.’

‘I beg your pardon, sir?’

‘No, sorry, I mean don’t cancel lunch, but cancel it at the fish restaurant.’

‘I thought it was your favourite restaurant, sir?’