Immediately, Müller could tell that security was strict. As well as plenty of radiation warning signs, there were guardhouses, barbed wire fences, and a general air of menace. They didn’t have any authorisations, and they hadn’t warned anyone about their visit.

As the guard at the gatehouse examined their IDs, they realised that was going to prove problematic.

‘You will have to turn round and park in the visitors’ car park over there, Comrade Hauptmann,’ said the guard. ‘Then come back here and wait in the waiting room. I will see if anyone can come and see you.’

*

They were indeed forced to wait, Tilsner regularly checking his watch – his expensive western watch – and then making sorties to the desk to demand some action. The guards looked disinterested.

‘We’ve let the directorate know that you are here,’ said the head guard. ‘If they are able to come and see you, they will. If you don’t have time to wait, then I suggest you write a letter asking for a proper appointment.’

Tilsner sat back down in a huff. ‘I’m not even sure he’s German. He seemed to have an accent to me. Russian?’

Müller shrugged. ‘It wouldn’t surprise me. I think the uranium mines are jointly owned by the Russians, aren’t they? The place is probably staffed by KGB agents, rather than the Stasi.’

Eventually, a pasty-faced balding besuited man made his way over to them.

Müller and Tilsner stood up to shake his hand.

‘I’m Horst Frank, one of the deputy directors of the mine. Come this way, Comrade Hauptmann, Comrade Oberleutnant, please.’ He led them into a side office, closed the door behind him, and invited them to sit in two chairs placed in front of a desk. He took the seat behind.

‘This is most irregular, I’m afraid. Visitors strictly need to make a prior appointment.’

‘We don’t need to actually visit the mine,’ explained Müller. ‘We’re simply seeking some information about one of your employees.’

‘Or former employees,’ added Tilsner.

‘Well, which is it?’ asked the man.

‘Well the woman in question had a pass to work here which expired at the end of last year,’ said Müller.

‘Mmm. And?’ said the man.

‘We need to know if she still works here,’ said Tilsner. ‘Her name’s Lotti Rolf.’

Müller detected a flicker of apprehension on Herr Frank’s face.

‘You know her?’ she asked.

‘Well . . . yes, but she didn’t have a particularly important role here. She was in charge of timekeeping.’

‘Was?’ asked Tilsner.

‘Yes. She left her position towards the end of last year.’

‘Why?’ asked Müller.

‘Ah,’ said Frank. ‘I’m not sure if I’m permitted to tell you that.’

‘This is a murder inquiry we’re working on,’ said Müller.

‘Still. There are questions of national security with an enterprise like this, I’m sure you understand.’