That evening while I was tidying up, Huang Yiyi knocked on the door and came in. In amongst the heaps of stuff that I had brought back from the Soviet Union, she quickly rooted out a picture of Anderov and myself. She recognized him immediately, and so the conversation naturally turned to Anderov and Sivincy. She said, ‘Anderov is an expert at cracking American ciphers, but RECOVERY was written by Sivincy so it’s going to be in the Russian style, which means that your skills are pretty useless.’

I nodded. ‘You know that Sivincy wrote a cipher called DIFFICULT CENTURY?’

‘Yes. She wrote it specially for the American military.’

‘The Americans gave Sivincy a job devising ciphers because they wanted to make it difficult for Anderov.’

‘Well, Anderov has cracked a lot of American ciphers, and they are really afraid of him. But Sivincy went to university with Anderov, and they were good friends who knew each other very well. Any cipher written by Sivincy will be designed to confuse Anderov.’

‘Right, so we can say that when the Americans first decided to employ Sivincy to write DIFFICULT CENTURY, their intention was to deliberately confuse Anderov. And only Sivincy could do that, because she is about the only person who knows his shortcomings.’

‘So we can assume that Sivincy will have hidden a lot of traps within DIFFICULT CENTURY that were specifically designed to get Anderov. So if you asked Anderov to break DIFFICULT CENTURY, he would be at a serious disadvantage, being fundamentally unable to crack the cipher.’ She glanced at me and smiled. ‘And if we asked Anderov’s student to work on it, he would fail.’

I knew that she meant me, but I was thinking about something completely different. I was silent for a moment, then I said, ‘RECOVERY is DIFFICULT CENTURY.’

She opened her eyes wide. ‘What did you just say?’

I repeated it, and then she said seriously, ‘How is that possible?’

‘It’s a fact. The American top brass were worried about the fact that Sivincy is Russian, and in the end they decided they did not dare use DIFFICULT CENTURY, so they sold it to Taiwan. The Taiwanese renamed it RECOVERY.’

She stood up. ‘Is this some kind of joke?’

I shook my head. ‘This is important. Is it likely that I would make a joke of it?’

She suddenly started shouting at me. ‘If you knew that, why on earth did you take the job? You really do have a fantastic opinion of yourself, to carry on when clearly you don’t have a hope in hell. Who do you think you are? Do you really imagine that you can just waltz in and everything will sort itself out?’