At that time Sino-Soviet relations were already pretty sensitive, and when I got to the train station my luggage was thoroughly searched. When my supervisor Anderov saw that, he yet again urged me not to go home. For days he had been trying to persuade me to stay, and just the night before we had had a long conversation. He analysed the future of Sino-Soviet relations and my probable future career, and told me that in his opinion going back to China was the worst possible option for me. He seemed to have already had some kind of premonition of the coming Sino-Soviet split, and suspected that when I got home I would quite possibly be set to cracking Russian ciphers, which would sully our deep friendship. He was hoping that I would stay and finish my master’s thesis and then go on to study for a PhD, concentrating on mathematical problems. He didn’t want me to get caught up in the world of cryptography. ‘This whole thing is an ideological issue,’ he said. ‘It is absolutely nothing to do with scholarship. My experience should be a lesson to you. I can’t go back, but there is absolutely no need for you to follow in my footsteps; you can just be an ordinary student.’

But I knew that this was impossible; you could say that from the time I was born I was already an ideological person. I have already mentioned that I am a revolutionary orphan; the Party brought me up, and if the Party needed me now, I had no right to refuse.

When they had finished searching my luggage, my supervisor asked me if I knew what kind of people had been looking through my stuff. I said that I didn’t know, and he told me that they were KGB. I guessed that he had already worked out who I really was, but I still pretended to be surprised and said, ‘How could that be?’

He laughed. ‘My friend, I think you should tell me the truth. Other than being a junior scholar at the Cryptography Research Centre at the Chinese Academy of Sciences, who are you?’

‘Why are you suddenly asking me that, Mr Anderov?’

‘Because recently you have become very mysterious to me.’

‘I have no secrets from you.’

‘My friend, you are lying.’ He pointed to the box containing Xiaoyu’s ashes which I was holding in my arms, and asked me how my wife had died. He said that he didn’t believe that it was a simple car crash. I swore that that was all it was. In fact I didn’t know myself how she had died. But I had to say that; I had to make him believe me.