‘I’m fine, thank you, sir.’ Frank was pleased he’d not yet removed his coat. He’d been warmer when he’d taken his dog for a walk just after dawn. He slipped his hands into his pockets, hoping von Helldorf wouldn’t notice.

‘The Kripo should have had this case from the beginning in my opinion.’

‘I agree, sir.’

‘You’d have solved it by now.’

‘One would hope so, sir.’

‘This is the file – getting it from them was like prising sweets from a spoilt child. Go away and study it, then get on with the case. How long do you think you’ll need – three, four days?’

‘To read the file, sir?’

‘No, Frank, to solve the case.’

It had already been dark for five hours when Frank finally finished reading the file marked Oberst Albert Kampmann. The only light in his office came from the Anglepoise lamp illuminating his desk and the glowing end of what must have been his thirtieth cigarette of the day.

He closed the file and looked at his notebook. He read through what he’d written, then turned to a fresh page and started writing again: just a few salient points, the most important ones. This was his method: to make notes as he went along, edit them, refine them and extract no more than a dozen key facts or questions to work through. It was a system that rarely failed, but he had a nagging feeling in his stomach that this case might prove to be the exception.

It was indeed a bloody mess.

Sometime in November – incredibly, they hadn’t even made a note of the date – the Gestapo had received an anonymous tip-off that an Oberst in the Luftwaffe’s scientific division based in the Air Ministry on Wilhelm Strasse was passing on secrets to the enemy: first name either Alfred or Albert. They soon established that there was only one Oberst in that division with the first name Alfred or Albert. Even the Gestapo could manage that: Oberst Albert Kampmann.

Their incompetence did not stop there. They failed to contact the security division of the Luftwaffe; they didn’t speak with anyone at the Air Ministry, not even any of their own people there. They simply put a tail on Kampmann, and according to the notebooks of the half-dozen or so idiots responsible for following him, they somehow managed to lose him for a crucial few minutes here, a few minutes there.