Then Gurevich mentioned how he missed the sense of danger he’d experienced during the war, the sheer exhilaration of facing down death every day: was this… odd?

‘Not at all: it was your way of coping with the stress of war and with the personal traumas in your life. Subconsciously you felt you had little to lose and therefore you were able to be reckless: it was as if you were finding a way of redeeming yourself. But a consequence of this behaviour was that this sense of risk and the excitement became like a drug. You became addicted to it.’

‘I miss it dreadfully sometimes, like I’m drawn to danger.’

‘Of course you will be – it’s an addiction, as I said, and you are experiencing what we call withdrawal symptoms. It will take time to get over; you will need to be patient. If you occasionally flirt with danger, that may help, though do be careful.’

Iosif Gurevich said this all made sense and thanked the psychiatrist very much. As he prepared to leave, the psychiatrist came over and spoke quietly in his ear.

‘On a personal note, Comrade, if you want my advice, stay here as long as you can. Things are really not good for us in Moscow.’

Now Kommissar Iosif Gurevich was taking the doctor’s advice and flirting with danger. He’d crossed into the British sector, the risk increased by the fact that the British knew who he was but mitigated by not having shaved for a few days and being dressed in shabby civilian clothes. To add to his cover, he was accompanied by a female NKVD officer called Yulia, who provided a useful extra set of eyes and ears as they walked arm in arm through the city.

‘Don’t worry,’ he assured her, ‘our papers are very good. We’re Polish Germans, a married couple from Poznań, trying to escape the damned Russians!’

He laughed, but she looked nervous: even jokes could be dangerous. Just look down, he told her. ‘Avoid eye contact; look for cigarette butts on the ground. Keep coughing: they’ll think you’re ill and will want to move you on.’

Their destination was on Cornelius Strasse, just south of the Tiergarten. He told Yulia to wait in the shell of a bombed-out building opposite. Lean against the wall, look exhausted; if any British soldiers say anything, ask them for money. They’ll soon leave you alone then!

Of course he could have asked them to come to him in East Berlin. It would have been more of an order than anything else and they’d have been obliged to do as he said. It was like that with these people: you were meant to be on the same side, but when one was a master and the other in effect a servant, relationships were more fraught.

The main reason he’d crossed the city to see them was that he didn’t want his own people to know what he was up to. They’d benefit in the long run – possibly – but in the meantime it was best to be discreet. That familiar sense of excitement, which had been building up all day, was now even more pronounced. His heart beat faster and his senses sharpened, and he felt more alive.