She laughed heartily. “I’m old enough to be your mother.”

“But my mother never made jian bing the way you do.”

In truth, his mother had never made jian bing. And had the world turned another way, Mei Yuan would not have had to. In another era she might, perhaps, have been a lecturer at the university, or a senior civil servant. Li inclined his head a little to catch the title of the book she had stuffed down the back of her saddle. Descartes’ Meditations. He looked at her plump little hands, scarred by a thousand tiny burns, and felt the pain of her life in his heart. A generation cursed by the twelve years of madness that was the Cultural Revolution. And yet if she had regrets, there was no hint of them in that dimpled smile and those mischievous eyes.

She had not missed him noticing her book. “I’ll lend it to you when I’m finished. He was an extraordinary man.” She smiled. “I think, therefore I am.” It would have taken her a long time to save up enough money to buy the book, so her offer to lend it to him was an extraordinary act of generosity and trust.

“Thank you,” he said. “I would like that. And I will be sure to return it to you when I have read it.” He filled his mouth with more jian bing. “So. Do you have an answer?”

She grinned. “The third person in the queue must have been his wife. You tried to make me think it was a man.”

“No, no. I didn’t try to make you think anything. You assumed it was a man. It was only when you stopped making that assumption that you realised who she was.”

She shook her head, still smiling. “Not very clever. But effective.”

“So what have you got for me?” He devoured the last of his jian bing and threw the wrapper in the bin.

“Two men,” she said. “And there is no ambiguity here.” She twinkled. “One of them is the keeper of every book in the world, giving him access to the source of all knowledge. Knowledge is power, so this makes him a very powerful man. The other possesses only two sticks. Yet this gives him more power than the other. Why?”

Li turned it over quickly in his head, but no solution came immediately to mind. “It’ll have to wait till tomorrow.”

She nodded. “Of course.”