Chen clearly didn’t like the way that she was taking charge, and with some resentment he got out a list of names and gave it to her. ‘Everyone’s here. Have a look. You can choose one or two comrades off this list to be your assistants.’

Huang Yiyi leafed idly through it and then gave it back to him. ‘This doesn’t tell me anything: it’s just a list of names.’

‘What do you want? Do you expect me to call them all in and let you pick them by interview?’

‘Not at all.’ She walked over to Chen’s desk and started inspecting one of the photographs placed under the glass top, asking, ‘Are these all your colleagues?’

‘Pretty much.’

Huang Yiyi continued her inspection for a moment, then she pointed to an old comrade wearing glasses. ‘Who’s he? A cryptographer?’

‘You can’t have him,’ Chen said.

‘Why not?’

Chen gestured to me to answer, and I explained that the old comrade was not at all well, and that he could not possibly do this kind of work. In actual fact, he was schizophrenic and completely insane.

What I wasn’t expecting was that with her next question Huang Yiyi would get right to the point. ‘Is he mad?’

‘How did you know?’ I asked.

‘I guessed as much. I looked at his eyes – terribly neurotic, just one step away from madness.’

‘He used to be the very best cryptographer we had,’ I said.

‘People like that are often only one step away from genius.’

‘He was driven mad by cryptography. He was under too much stress and his mind just snapped like an over-tight violin string.’

‘Like Nash,’ she said.

‘Who?’

‘John Nash, one of the mathematicians behind game theory. He was driven mad by cryptography too.’

Chen suddenly interrupted. ‘You’re also mad.’ He paused. ‘We’re all mad.’

His words left Huang Yiyi flabbergasted.

I understood what Comrade Chen was trying to say. From start to finish he had his own perspective on the problem of having to decrypt RECOVERY. He thought that our decision to crack it was arbitrary and had not been properly thought through; that it was absolutely absurd; that we were crying for the moon; that this was mad. The previous night he had come to my room to explain his reasoning. Now he repeated it for Huang Yiyi.