Weijing runs a pharmacy in Kowloon, the notorious crime town of old Hong Kong, where he also manufactures drugs for criminal syndicates as a side business. One day, the head of the district from the syndicate leaves a random guy in his care, and Weijing is suddenly left alone with a guy whose origin, identity, and purpose are entirely shrouded in mystery. But as the two spend more time together, their curiosity about each other eventually develops into something more.