Thirty minutes later, when the whistles had blown and the sirens cranked to sound the all-clear, there seemed little point in going back to bed. So I bought an extra litre off the Bolle milkman and cooked myself an enormous omelette.

Inge arrived at my office at just after nine. Without much ceremony she sat down on the other side of my desk and watched me finish making some case notes.

‘Did you see your friend?’ I asked her after a moment.

‘We went to the theatre.’

‘Yes? What did you see?’ I found that I wanted to know everything, including details that had no bearing on the man’s possible knowledge of Paul Pfarr.

‘The Base Wallah. It was rather weak, but Otto seemed to enjoy it. He insisted on paying for the tickets, so I didn’t need the petty cash.’

‘Then what did you do?’

‘We went to Baarz’s beer restaurant. I hated it. A real Nazi place. Everyone stood and saluted the radio when it played the Horst Wessel Song and Deutschland Über Alles. I had to do it too, and I hate to salute. It makes me feel like I’m hailing a taxi. Otto drank rather a lot and became very talkative. I drank quite a lot myself actually - I feel a bit rough this morning.’ She lit a cigarette. ‘Anyway, Otto was vaguely acquainted with Pfarr. He says that Pfarr was about as popular as a ferret in a gumboot at the DAF, and it’s not difficult to see why. Pfarr was investigating corruption and fraud in the Labour Union. As a result of his investigations, two treasurers of the Transport Workers Union were dismissed and sent to KZs, one after the other; the chairman of the Koch Strasse shop-committee of Ullstein’s, the big printing works, was found guilty of stealing funds and executed; Rolf Togotzes, the cashier of the Metal Workers Union, was sent to Dachau; and a lot more. If ever a man had enemies, it was Paul Pfarr. Apparently there were lots of smiling faces around the department when it became known that Pfarr was dead.’

‘Any idea what he was investigating at the time of his death?’

‘No. Apparently he played things very close to his chest. He liked to work through informers, amassing evidence until he was ready to make formal charges.’

‘Did he have any colleagues there?’

‘Just a stenographer, a girl by the name of Marlene Sahm. Otto, my friend, if you can call him that, took quite a shine to her, and asked her out a couple of times. Nothing much came of it. That’s the story of his life, I’m afraid. But he remembered her address though.’ Inge opened her handbag and consulted a small notebook. ‘Nollendorfstrasse, Number 23. She’ll probably know what he had been getting up to.’

‘He sounds like a bit of a ladies’ man, your friend Otto.’