Just inside the doors, a long and patiently waiting queue of people snaked across the breadth of the shop. The object of their vigilance was a consultation with an old, pinched-faced man perched in a booth off to the left. This retired doctor of medicine was, apparently, slow in dispensing his sagacity, and Li had no intention of waiting his turn. He pushed his way to the head of the queue, displaying his Ministry ID. Margaret hurried after him, eliciting odd and occasionally resentful stares. But no one voiced any objection. Li and Margaret entered the booth as a girl in her early twenties emerged, pasty-faced and spotty-cheeked, clutching a prescription and looking distinctly worried. The old doctor looked at Li’s ID for a long time before examining his face carefully and then inviting them both to sit. He barely gave Margaret a second glance. “What can I do for you, Detective?” he asked.

“I’m interested in one of your patients, Chao Heng.”

The doctor tipped his head in Margaret’s direction. “Who is she?”

“An American doctor. A pathologist helping us with a case.”

The old man turned to Margaret, eyeing her now with interest. “Where did you train?” he asked her in perfect English.

She was taken aback. “The University of Illinois.”

“Ah. I spent some time at the University of California, Davis Medical School. A research project on glandular cancer with my very good friend Dr. Hibbard Williams. Endocrinology is his speciality. Perhaps you have heard of him?”

“I’m afraid not.” She frowned. “I thought you were a practitioner of traditional Chinese medicine.”

“I studied both traditional Chinese and Western medicines. There is much that each can learn from the other. What is your speciality?”

“Burn victims.”

His nose wrinkled in distaste. “How unpleasant.”

Li interrupted. “Chao Heng did consult with you? Is that right?”

The doctor nodded. “Mr. Chao, yes.”

“I understand that he was unwell for some time.”

“Has something happened to him?”

“He was murdered.”

“Ah.” The doctor seemed unconcerned. “How unfortunate. But he was dying anyway.”

“What of?” Margaret asked.

“I have no idea. I treated his symptoms for about six months but nothing worked for him. Eventually I suggested to him that he see a former colleague of mine at the Beijing Hospital in Dahua Lu. He was not very keen. He was a great believer in traditional remedies. But there was nothing more I could do for him.”

“What were his symptoms?” Margaret was curious.

“They were many,” the old doctor said, shaking his head. “He suffered from exhaustion and diarrhoea, and he had frequent fevers. He had recurrent bouts of thrush and a cough that would not go away. He later developed swollen glands in the groin and the armpits. He was losing a lot of weight latterly. Some of his symptoms responded to treatment, at least for a time. But they always came back.”