If Margaret had been expecting some impressive showpiece building to house the headquarters of Section One, she would have been disappointed by the undistinguished brick block skulking anonymously behind the trees. From the street there was nothing to suggest that this was the nerve centre of Beijing’s fight against serious crime. Only a well-informed and observant onlooker would have spotted that the registration numbers of all the unmarked cars parked in the street began with the Chinese character representing the word Capital, followed by a zero—the telltale registration mark of all Beijing police vehicles. Li led Margaret, followed by Lily, in through the side entrance and up to the top floor. To his extreme discomfort the detectives’ room was full of officers sitting around poking chopsticks into carry-out dishes of noodles and rice, jars of green tea sitting on desks. There was an odd air of expectation as he walked in, and a hush that descended on their conversation, even before Margaret appeared in the doorway. Her appearance served only to heighten an already tense atmosphere. Detectives sat up self-consciously, wondering, clearly, who she was and why she was there. But Li was determined to play it cool.

“Qian,” he said. “We’ve made an identification of our burn victim. His name is Chao Heng, graduated from the American University of Wisconsin in 1972 in . . .” He glanced at the piece of paper in his hand, “. . . microbial genetics. Whatever that is. Let’s get an address and find out what we can about him ASAP. Okay?”

Qian almost sat to attention. “I’m on it already, boss.” And he reached for a telephone. But he hesitated before dialling, watching, like everyone else in the room, as Li opened the door to his office. There were some stifled sniggers as he stopped in his tracks, confronted by the bizarre figure of an old man with long, wispy white hair and an equally long silver goatee. He was wearing what could only be described as black pyjamas and was sitting cross-legged on Li’s desk. Margaret peered round Li to see what the cause of the hilarity was.

“What the hell . . .” Li looked at the old man in consternation, aware now of some less restrained laughter behind him. Lily had come into the room and was staring open-mouthed at the old man.

“Who is he?” Margaret finally asked, perplexed by the bizarre nature of the scene unfolding before her.

“No idea,” Li said. And in Chinese to the old man, “Would you like to tell me what you are doing in my office?”

More laughter from the detectives’ room as the old man emerged from some deep contemplation and turned on Li a wizened and solemn face. “Bad feng shui,” he said. “Ve-ery bad feng shui.”

“Feng shui?” Margaret said, recognising the words. “I know what that is.”

Li turned to her in astonishment. “You do?”