“What’s so funny?” she asked.

“Old Chen,” he said. “He is a prickly old bastard, but he’s not stupid. I told him I thought the key to Chao’s murder was in his blood. He said,”—and Li was careful to recall the exact words—“‘then find another key. There’s always a back door.’”

“As long as you let me help to unlock it.” Margaret raised an appealing eyebrow.

“You’ve got a plane to catch.”

“A lot can happen in . . .” She checked her watch. “. . . Seventeen and a half hours.”

II

Li turned the Jeep down Beijingzhan Street, and ahead of them rose the twin towers of Beijing railway station, where Old Yifu would arrive back from Sichuan some time that evening. Li had taken a circuitous route to Chongwenmen to avoid the traffic that had ground to its habitual afternoon standstill on the second ring road. He had finally summoned up the courage to ask Margaret what had happened to make her quit the university. And she had told him: about missing her lecture, about the attitude of Jiang and his staff, about her row with Bob. Now he shook his head and said, “I am so sorry, Margaret.”

“Why? It’s not your fault.”

“If I had taken you back to your hotel instead of my apartment none of this would have happened.”

“If I hadn’t got drunk . . .” She didn’t need to finish. “Well, anyway, it’s that little bitch, Lily Peng, that I blame. It was her that snitched on us.”

Li shrugged. “If it had not been her it would have been someone else—the duty policeman at the apartments, the staff at the Friendship . . . But there was no reason for you to quit.”