On a rainy night, the textile tycoon's only son falls from the roof of the mountain villa, landing face down and dying in the muddy water of a flower bed. The most famous Japanese police inspector in the capital determines this is a murder staged with moss, and the killer is the victim's chronically abused wife; the private detective Nangong Huan, invited by the victim's father, stays silent and squats by the muddy ground looking at an umbrella. Beneath the moss there is a younger brother, and beneath the younger brother there is yet another person—a person who has hardly spoken a few words throughout the entire film.