I walked carefully across the badly rusted roof on all fours, not daring to stand up straight and concentrate all my weight on one point. At the back of the roof I looked down into a small courtyard which led on to the pension. Most of the windows in the rooms were shrouded with dirty net curtains, and there was no sign of life at any of them. I searched for a way down, but there was no drainpipe, and the wall to the adjoining property, the German accountant’s, was too low to be of any use. It was fortunate that the rear of the pension obscured the view to the garage of anyone who might have chanced to look up from poring over a dull set of accounts. There was no choice but to jump, although it was a height of over four metres. I made it, but it left the soles of my feet stinging for minutes afterwards, as if they had been beaten with a length of rubber hosing. The back door to the garage was not locked and, but for a pile of old car tyres, it was empty. I unbolted the double doors and admitted Inge. Then I bolted them again. For a moment we stood in silence, looking at each other in the half darkness, and I nearly let myself kiss her. But there are better places to kiss a pretty girl than a disused garage in Kreuzberg.

We crossed the yard, and when we came to the back door of the pension, I tried the handle. The door stayed shut.

‘Now what?’ said Inge. ‘A lock-pick? A skeleton key?’

‘Something like that,’ I said, and kicked the door in.

‘Very subtle,’ she said, watching the door swing open on its hinges. ‘I assume you’ve decided that there’s nobody here.’

I grinned at her. ‘When I looked through the letter-box I saw a pile of unopened mail on the mat.’ I went in. She hesitated long enough for me to look back at her. ‘It’s all right. There’s nobody here. Hasn’t been for some time, I’d bet.’

‘So what are we doing here?’

‘We’re having a look around, that’s all.’

‘You make it sound as if we were in Grunfeld’s department store,’ she said, following me down the gloomy stone corridor. The only sound was our own footsteps, mine strong and purposeful, and hers nervous and half on tiptoe.