‘I need you to come with me.’

On the way to Reinhard Lange’s address we called in at my office to collect his letters. I poured us both a large glass of schnapps and explained something of what had transpired that evening.

‘Lange’s the weak link. I heard them say so. What’s more, he’s a lemon-sucker.’ I drained the glass and poured another, inhaling deeply of it to increase the effect, my lips tingling as I held it on my palate for a while before swallowing. I shuddered a little as I let it slip down my backbone and said: ‘I want you to work a Vice-squad line on him.’

‘Yes? How heavy?’

‘Like a fucking waltzer.’

Becker grinned and finished his own drink. ‘Roll him out flat? I get the idea.’ He opened his jacket and took out a short rubber truncheon which he tapped enthusiastically on the palm of his hand. ‘I’ll stroke him with this.’

‘Well, I hope you know more about using that than you do that Parabellum you carry. I want this fellow alive. Scared shitless, but alive. To answer questions. You get it?’

‘Don’t worry,’ he said. ‘I’m an expert with this little india rubber. I’ll just break the skin, you’ll see. The bones we can leave until another time you give the word.’

‘I do believe you like this, don’t you? Scaring the piss out of people.’

Becker laughed. ‘Don’t you?’

The house was on Lutzowufer-Strasse, overlooking the Landwehr Canal and within earshot of the zoo, where some of Hitler’s relations could be heard complaining about the standard of accommodation. It was an elegant, three-storey Wilhelmine building, orange-painted and with a big square oriel window on the first floor. Becker started to pull the bell as if he was doing it on piecework. When he got tired of that he started on the door knocker. Eventually a light came on in the hall and we heard the scrape of a bolt.

The door opened on the chain and I saw Lange’s pale face peer nervously round the side.

‘Police,’ said Becker. ‘Open up.’

‘What is happening?’ he swallowed. ‘What do you want?’

Becker took a step backwards. ‘Mind out, sir,’ he said, and then stabbed at the door with the sole of his boot. I heard Lange squeal as Becker kicked it again. At the third attempt the door flew open with a great splintering noise to reveal Lange hurrying up the stairs in his pyjamas.

Becker went after him.

‘Don’t shoot him, for Christ’s sake,’ I yelled at Becker.