Steglitz is a prosperous, middle-class suburb in south-west Berlin. The red bricks of the town hall mark its eastern side, and the Botanical Gardens its west. It was at this end, near the Botanical Museum and the Planzen Physiological Institute, that Frau Hildegard Steininger lived with her two children, Emmeline aged fourteen, and Paul aged ten.

Herr Steininger, the victim of a fatal car crash, had been some brilliant bank official with the Privat Kommerz, and the type that was insured up to his hair follicles, leaving his young widow comfortably off in a six-room apartment in Lepsius Strasse.

At the top of a four-storey building, the apartment had a large wrought-iron balcony outside a small, brown-painted French window, and not one but three skylights in the sitting-room ceiling. It was a big, airy sort of place, tastefully furnished and decorated, and smelling strongly of the fresh coffee she was making.

‘I’m sorry to make you go through all this again,’ I told her. ‘I just want to make absolutely sure we didn’t miss anything.’

She sighed and sat down at the kitchen table, opening her crocodile-leather handbag and finding a matching cigarette box. I lit her and watched her beautiful face tense a little. She spoke like she’d rehearsed what she was saying too many times to play the part well.

‘On Thursday evenings Emmeline goes to a dancing class with Herr Wiechert in Potsdam. Grosse Weinmeisterstrasse if you want to know the address. That’s at eight o’clock, so she always leaves here at seven, and catches a train from Steglitz Station which takes thirty minutes. There’s a change at Wannsee I think. Well, at exactly ten minutes past eight, Herr Wiechert telephoned me to see if Emmeline was sick, as she hadn’t arrived.’

I poured the coffee and set two cups down on the table before sitting opposite her.

‘Since Emmeline is never, ever late, I asked Herr Wiechert to call again as soon as she arrived. And indeed he did call again, at 8.30, and at nine o’clock, but on each occasion it was to tell me that there was still no sign of her. I waited until 9.30 and called the police.’

She sipped her coffee with a steady hand, but it wasn’t hard to see that she was upset. There was a wateriness in her blue eyes, and in the sleeve of her blue-crepe dress could be seen a sodden-looking lace handkerchief.

‘Tell me about your daughter. Is she a happy sort of girl?’

‘As happy as any girl can be who’s recently lost her daddy.’ She moved her blonde hair away from her face, something she must have done not once but fifty times while I was there, and stared blankly into her coffee cup.