Murakami (Toshirô Mifune), a young police officer in 1940s Tokyo, finds that his gun was stolen while he was riding a packed bus. With his position in jeopardy, Murakami, aided by veteran officer Sato (Takashi Shimura), tries to locate his missing weapon. Together, they head to some of the worst parts of the city -- and to the forefront of crime. When Murakami learns that his gun has been used in a murder, his search escalates.