She took it, then almost dropped it in disgust. Once again, she, Tilsner and Schmidt were being given the runaround.

The name on the card: Major Rüdiger Bahlow. Ministry for State Security.

*

When they got back to the incident room after the fruitless visit to the university, Bahlow was waiting for them, leaning back in Müller’s chair, twiddling his thumbs. Müller almost expected him to stay there and let her stand, but clearly the man had some manners.

‘Sorry, Comrade Müller. I was just resting my legs while waiting for you.’ He noticed the dressing on the back of Müller’s head, and seemed genuinely concerned. ‘I hope you’re all right. If this isn’t a convenient moment, I can come back later.’

Müller drew in a long breath, then exhaled. ‘No. We wanted to talk to you as well. And this is as good a time as any. The reason I’ve got a dressing on my head is that someone decided to whack me on the skull yesterday evening, a bit like our Concrete Man. Do you know where that happened?’

‘No,’ replied Bahlow, looking puzzled. ‘Should I?’

‘Perhaps,’ said Tilsner. ‘It was in an apartment where we found your fingerprints.’

‘I hope you’re not suggesting I had anything to do with Comrade Müller’s injuries.’

‘We’re not suggesting that, no,’ said Müller. ‘I don’t think even your lot would be clumsy enough to launch an unprovoked attack on a Kriminalpolizei officer. Nevertheless, your fingerprints were found in several places in an apartment we think may be linked to our inquiries.’

Bahlow shrugged, looking unconcerned. ‘Would you care to enlighten me where exactly?’

‘In Sonnenstein, on the edge of Pirna,’ said Tilsner. ‘At the apartment of a citizen named Lotti Rolf.’

Müller watched Bahlow’s face. Trying to detect if there was any sign of alarm – that the man may have been involved in the raid on Rolf’s apartment, and somehow made a mistake, forgetting to cover his hands with gloves, or taking them off at some point. But there wasn’t a flicker in the eyes or facial expression.

‘That’s easy to explain,’ said the Stasi officer. ‘There’s no reason why I have to tell you this, and it must remain absolutely confidential. She’s an unofficial informer for the Ministry for State Security.’ Then he looked hard at Müller. ‘Ask your deputy if you’re uncertain what one of those is, or what their function is.’ He allowed himself a small smirk. ‘I’m her handler – we sometimes meet at her apartment for briefings. It’s as simple as that. So if she’s featuring in your investigation, and you need to interview her, make sure you ask my department first. Is that clear?’