Li shook his head. “They have consulting doctors there. Usually retired. It’s a way to augment their pensions.”

“And they prescribe herbal medicine?”

“Traditional Chinese medicine,” Liu Xinxin said. “Very good medicine. Make you well very fast.”

“Well, he certainly didn’t get reverse transcriptase and protease inhibitors in a herbal medicine shop,” Margaret said.

Dazhalan was a jumble of street markets and curiosity shops in narrow, medieval hutongs just south of Qianmen. Li and Margaret pushed their way through frenetic crowds of shoppers. Tinny music blasted from loudspeakers hanging at every corner. Red and yellow character banners zigzagged above their heads. Shopfronts were fantastic creations of tiled and curling eaves supported on intricate and colourfully painted beams and pillars. “During the Ming Dynasty,” Li told her, “there were great wicket gates here that closed off the inner city at night. Dazhalan means, literally, ‘big stockades.’ In imperial Beijing, shops and theatres were not permitted in the centre of the city. So they opened up here, just outside the gates. It was the place to come on a dull Beijing night.”

They passed a four-hundred-year-old emporium selling pickle and sauce, a restaurant offering imperial snacks, a shop which had been dealing in silks and wool and furs for more than a hundred years. “This used to be the red-light district,” Li said. “Until the communists shut all the brothels down in 1949 and sent the girls to work in factories.” And suddenly he remembered Lotus, and his promise to Yongli. He cursed inwardly, but he was in no position to do anything about it now.

Beneath a colourful and beautifully ornate canopy, white marble lions in wrought-iron cages guarded the entrance to the Tongrentan Traditional Medicine Shop, purveyor of herbal concoctions since 1669. But they had not prevented several young men from slipping into the shade of the canopy and curling up on the cool marble slabs to sleep away the afternoon. Li and Margaret stepped over an older man who was snoring aggressively and pushed through glass doors into the deliciously cool air-conditioned interior.

It was not what Margaret had been expecting. Somehow the notion of traditional Chinese herbal medicine had conjured in her mind a dark and dingy shop, with daylight slanting in through old wooden shutters, and an old man with a long, wispy white beard serving behind a counter piled high with jars and bottles of exotic pills and lotions. Instead it was large and bright and modern. A gallery on the second floor was supported on red-and-gold pillars and overlooked the first-floor shop where the pills and lotions were displayed in very ordinary cardboard boxes in fluorescently lit glass display cabinets. High above them, huge glass lampshades were painted with scenes of imperial China and hung with long yellow tassels. The medicines themselves, however, surpassed even her wildest expectations: dried seahorses and sea slugs, tiger bone, rhino horn and snake wine, cures for everything from fright to encephalitis—or so they claimed.