From the outside the Schultheiss Brewery in Kreuzberg, with its uniform red brick, numerous towers and turrets, as well as the fair-sized garden, made it seem more like a school than a brewery. But for the smell, which even at two a.m. was strong enough to pinch the nostrils, you might have expected to find rooms full of desks instead of beer-barrels. We stopped next to the tent-shaped gatehouse.

‘Police,’ Becker yelled at the nightwatchman, who seemed to like a beer himself. His stomach was so big I doubt he could have reached the pockets of his overalls, even if he had wanted to. ‘Where do you keep the old beer-barrels?’

‘What, you mean the empties?’

‘Not exactly. I mean the ones that probably need a bit of mending.’

The man touched his forehead in a sort of salute.

‘Right you are, sir. I know exactly what you mean. This way, if you please.’

We got out of the cars and followed him back up the road we had driven along. After only a short way we ducked through a green door in the wall of the brewery and went down a long and narrow passageway.

‘Don’t you keep that door locked?’ I said.

‘No need,’ said the nightwatchman. ‘Nothing worth stealing here. The beer’s kept behind the gate.’

There was an old cellar with a couple of centuries of filth on the ceiling and the floor. A bare bulb on the wall added a touch of yellow to the gloom.

‘Here you are then,’ said the man. ‘I guess this must be what you’re looking for. This is where they puts the barrels as needs repairing. Only a lot of them never get repaired. Some of these haven’t been moved in ten years.’

‘Shit,’ said Korsch. ‘There must be nearly a hundred of them.’

‘At least,’ laughed our guide.

‘Well, we’d better get started then, hadn’t we?’ I said.

‘What exactly are you looking for?’

‘A bottle-opener,’ said Becker. ‘Now be a good fellow and run along, will you?’ The man sneered, said something under his breath and then waddled off, much to Becker’s amusement.

It was Illmann who found her. He didn’t even take the lid off.

‘Here. This one. It’s been moved. Recently. And the lid’s a different colour from the rest.’ He lifted the lid, took a deep breath and then shone his torch inside. ‘It’s her all right.’

I came over to where he was standing and took a look for myself, and one for Hildegard. I’d seen enough photographs of Emmeline around the apartment to recognize her immediately.

‘Get her out of there as soon as you can, Professor.’

Illmann looked at me strangely and then nodded. Perhaps he heard something in my tone that made him think my interest was more than just professional. He waved in the police photographer.

‘Becker,’ I said.

‘Yes, sir?’