The rain of the previous night had washed some of the dust and humidity out of the atmosphere, and the air was fresher as he followed his habitual route to work, cycling north along Chaoyangmen Nanxiaojie Street. Overhead the sky was blue, instead of a burned-out grey, and the sun was hot on his skin. He was still preoccupied with thoughts of Margaret. Had she been disappointed that nothing had happened between them last night? He had thought she seemed relieved. It was strange, he reflected, how she seemed always on the verge of intimacy, as though they had once known each other well, like old lovers. She seemed often about to touch him, or kiss him, but held back at the last as if realising that she didn’t, after all, know him. Or perhaps it was simply that the habit of casual intimacy, born of years living with the man she had married, was hard to break, and that, really, it had nothing to do with Li at all.

At the corner of Dongzhimennei he waved at Mei Yuan as he passed, and called out, “Sorry, I have no time this morning.” She stood up to wave him over, a sense of urgency in her signalling. But he was already out into the stream of traffic crossing the main road. “Later,” he shouted back at her.

The corridors of Section One were still crowded with citizens awaiting interrogation about the itinerant from Shanghai, or about what they had seen or not seen in Ritan Park two mornings previously. The detectives’ room was empty except for Detective Qian, who was still writing up his report on events in the park the night before. He seemed agitated and tipped his head towards Li’s office. “Chief’s waiting for you in there.”

Li braced himself and strode confidently through the door. “Morning, Chief. Big breakthrough last night.”

Chen was sitting at Li’s desk flicking idly through a number of reports awaiting Li’s attention. He looked up and said, grimly, “Is that in your personal or your professional life?”

“What do you mean?”

“Oh, come off it, Li!” Chen slammed the flat of his hand down on the desk. “We both know that Dr. Campbell stayed at your apartment last night. What in God’s name did you think you were playing at?”

“She’d had too much to drink, Chief. She wasn’t feeling well, so I let her stay over. There wasn’t any more to it than that. She slept in Old Yifu’s room.”

“Damn you, Li. She’s a foreigner. You are an official of the state!”

“My relationship with Dr. Campbell is strictly work, Chief,” Li protested.