The doctor shrugged. “Several each year. They usually just stop breathing in their seats. Older people mostly, out for a little adventure in Tibet. They don’t bother to read our literature that points out that Beijing has an elevation of one hundred forty feet and the train takes them to sixteen thousand feet. We very clearly recommend in our brochures that they spend two or three days acclimatizing in Xining but almost no one does.” He lifted one of the man’s hands, which seemed to be thawing. “Look at the cyanosis!” He grew more eager. “Can I take photographs?”

“When the army is done,” Shan said.

“Coach B, Seat 21A,” the conductor announced behind Shan. “One-way ticket.”

The doctor bent to examine the dead man’s eyes. “One-way is right,” he murmured.

“So he was a paying passenger,” Shan said, glancing at Tan. “One of the lieutenants will go with you to collect any luggage and belongings at his seat.” Tan nodded his approval.

“Of course,” the conductor said, with obvious relief. By now it was not clear if he was more uncomfortable with the dead man or with the colonel.

Shan turned to the doctor. “It was pulmonary edema then?”

“Yes, of course. Look at the fingers.” He pointed to the mouth, where a pink crust was melting. “Look at the color of that sputum. A textbook case.”

“Which makes it natural causes,” Tan said to the doctor, though he was pointedly looking at Shan, warning him not to argue.

“Yes, yes. The autopsy will find his lungs full of fluid.”

“Thank you, Doctor. You may share your conclusion with the detectives waiting outside so they understand no crime was committed. The body may be removed as soon as we clear out my cargo.”

“They will want to see the scene just as he was discovered,” the doctor said.

Tan gestured toward the crates that bore the insignia of the People’s Liberation Army, then leaned toward the doctor and lowered his voice. “National security, comrade,” he stated. “National security.” The doctor’s eyes went round, and he vigorously nodded. “When Public Security asks, it was natural causes, an accident.”

“His employer had cargo here,” Shan inserted, pointing to the large crate. “He came to check on it. He didn’t recognize the onset of his altitude sickness. He became dizzy and fell against the control panel after the door behind him closed. Unfortunately, there was no way for him to get out, no way for him to alert someone to save him. He couldn’t go out the rear door with the train speeding through the mountains. He sat and piled blankets around him, thinking he would just ride that way to Lhasa. But to be complete, you will have the usual tests done and report back to Colonel Tan with the results.”

The doctor began backing away. He looked frightened again. “Of course,” he agreed. “Very straightforward.”