‘Get your coat on, you’re coming with us.’

‘I can’t, I…’ His heart beat faster and he felt nauseous.

‘Really? It must be a very important social occasion if it’s preventing you from doing what you’re told.’

Hoffman cleared his throat. ‘You’re not in trouble, Willi, but your cooperation would be very much appreciated.’

‘Where are we going?’

The Russian reached into his inside coat pocket and Kühn backed against the wall. He relaxed when some papers were handed to him. ‘If we get stopped, this is the pass you show, but let Paul do the talking. We should be all right, though; we’ll take a longer route, but it’s a safer one.’

‘I need to know where you’re taking me.’

‘You’re going on a trip to the east, Willi.’

The events that night in his office on Behrenstrasse reminded Iosif Gurevich of a play he’d seen in Moscow before the war. He remembered little of it other than that it was predictably earnest, with long periods of silence punctuated by speeches that sounded like editorials from Izvestiya, though without the jokes.

A recurring scene saw a series of workers at a collective farm summoned to the party chairman’s office, each eager to take the blame for some unspecified misdemeanour. The succession of people coming through his door that evening reminded him of those hapless workers: the put-upon Yegorov; Fyodorov; Hoffman, and now Willi Kühn, who stood in front of him blinking in the bright light. Gurevich felt like the party chairman on the collective farm, studying his most recent visitor as he stood nervously in front of him, twirling his hat round against his chest.

‘Kühn, I understand that when you met Wolfgang Steiner in October, he gave you a telephone number to contact him in the event of you having a message from Bormann. That is correct?’

‘Yes, sir and I gave that number to Herr Hoffman when I met him and a very charming lady colleague of his on Kurfürstendamm. Do you not remember, Paul?’

‘I know you gave him the number, Kühn, I’m not disputing that: I have it here in front of me. What I want to know is whether Steiner gave you any idea as to where he was?’

Kühn shook his head. ‘I did ask him where he was based – I think that’s how I put it – but he didn’t tell me. That’s when he gave me the telephone number. Why don’t you try and trace it?’

‘Thank you very much, Kühn, I had no idea you’d make such a brilliant detective – maybe you could join Hoffman in the Volkspolizei. Yes of course we’ve tried to trace that number. Fyodorov…’

‘It’s untraceable sir: obviously we checked it out as soon as we got it. The Nazis had a sophisticated telephone system in many respects, and it seems they were able to set up numbers and then remove any record of where they were located. Our engineers suspect they may have used some kind of shadow system, where a property has a primary telephone number and then a secondary number operating from the same line that no one knows about.’