They sat in silence for several moments, staring at the chessboard, but their minds were not on chess. Finally, Old Yifu clapped his hands to break their reverie and said, “Your move.”

Li blinked at the board and moved his Castle, without thinking, to threaten his uncle’s Bishop. Old Yifu frowned, perplexed, unable to see the logic in the move but suspecting a trap. “So,” he said. “Tell me about your murders.” And so Li told him—about the burning body in the park, about the small-time drug dealer found on waste ground, about the itinerant lying with a broken neck in a condemned siheyuan. “And the connection?” his uncle asked. Li told him about the cigarette ends. Old Yifu frowned. “Hmmm. Not much of a connection. Can you prove they were all smoked by the same man?”

“Not yet.”

“Hmmm.”

“What does that mean?”

“It means, hmmm.” Old Yifu took another of Li’s Soldiers. “Perhaps these cigarette ends do indicate a connection. But if you focus too much on that, you may miss other links.”

Li told him about the drugs connection and his intention to “have a chat” tomorrow with The Needle.

“Hmmm.”

“What this time?”

“The drugs connection links only the body in the park and the stabbing, correct?”

“Correct. But there may well be a drugs connection with the itinerant.”

“But you don’t know that.”

“Not yet, no.” Li was becoming exasperated. “But we’re interviewing every itinerant who has registered in Beijing in the last six weeks. We’re pulling in every two-jiao drug dealer and junkie. If there’s a link, we’ll find it.”

“Of course you will.” Old Yifu took Li’s Bishop. “And if there isn’t, you won’t. And you’ll be six months down the line and no further on.”

“So what are you saying? That it’s a waste of time interviewing these people?”

“Oh no, you must. There is no substitute for diligence in police work. ‘Where the tiller is tireless, the land is fertile.’”

Li was tiring of his uncle’s wisdom. He took a Horse with a Bishop, and banged the wooden disk down on the stone table, the first piece he had taken. “Jiang!” he said, having put his uncle’s King in check.

“The thing is,” said old Yifu, quite unperturbed, “as the famous American inventor, Thomas Alva Edison, once said, ‘Genius is one per cent inspiration, ninety-nine per cent perspiration.’ All the perspiration in the world will get you nowhere without that one spark of inspiration.” He blocked the check with his Guide and watched as Li manoeuvred his Horse, then slid his Cannon across the board. “Jiang si le!”

Li stared at his King in disbelief. There was nowhere it could go. It was indeed checkmate. He sat back and folded his arms. Of course, he hadn’t been concentrating. “So where do I look for this inspiration?” he asked.