It might be June, or it might be July. I can no longer keep track of the days. It’s that halfway point of a Hong Kong summer, when the heat turns everything soupy. The days and nights run together, and the usual strictures of time and space begin to crumble. How long have I been with my British boyfriend? Long enough for him to have bought a new camera. He’s an avid photographer, one who’s always itching for a worthy subject to capture. One day he finds one: Let’s go off the beaten track, to Xinjiang, China’s westernmost province, to…