‘Too bad you didn’t get one for Interrogation,’ she said. ‘You know, she got really rattled when you suggested that Pfarr’s mistress might be dead.’

‘Well, what would you have me do - pistol-whip it out of her?’

‘I just meant that it was too bad she wouldn’t talk, that’s all. Maybe she will change her mind.’

‘I wouldn’t bet on it,’ I said. ‘If she does work for the Gestapo then it stands to reason that she’s not the sort who underlines verses in her Bible. And did you see those muscles? I bet she’s their best man with a whip or a rubber truncheon.’

We picked up the car and drove east on Bülowstrasse. I pulled up outside Viktoria Park.

‘Come on,’ I said. ‘Let’s walk awhile. I could do with some fresh air.’

Inge sniffed the air suspiciously. It was heavy with the stink of the nearby Schultheis brewery. ‘Remind me never to let you buy me any perfume,’ she said.

We walked up the hill to the picture market where what passed for Berlin’s young artists offered their irreproachably Arcadian work for sale. Inge was predictably contemptuous.

‘Have you ever seen such absolute shit?’ she snorted. ‘From all these pictures of the muscle-bound peasants binding corn and ploughing fields you would think we were living in a story by the Brothers Grimm.’

I nodded slowly. I liked it when she became animated on a subject, even if her voice was too loud and her opinions of the sort that could have landed both of us in a KZ.

Who knows, with a bit more time and patience she might have obliged me to re-examine my own rather matter-of-fact opinion of the value of art. But as it was, I had something else on my mind. I took her by the arm and steered her to a collection of paintings depicting steel-jawed storm-troopers that was arranged in front of an artist who looked anything but the Aryan stereotype. I spoke quietly.

‘Ever since leaving the Sahms’ apartment, I’ve had the idea that we were being followed,’ I said. She looked around carefully. There were a few people milling around, but none that seemed especially interested in the two of us.

‘I doubt you’ll spot him,’ I said. ‘Not if he’s good.’

‘Do you think it’s the Gestapo?’ she asked.

‘They’re not the only pack of dogs in this town,’ I said, ‘but I guess that’s where the smart money is. They’re aware of my interest in this case and I wouldn’t put it past them to let me do some of their legwork.’

‘Well, what are we going to do?’ Her face looked anxious, but I grinned back at her.