Masao is falsely accused and jailed for the murder of a loanshark to whom he owed a lot of money. His sister Kiriko makes the long trip to Tokyo, specifically to accost Otsuka, Japan's top criminal defence lawyer, and plead with him to take her brother's case. They live in KitaKyushu which, though a city, she contends that the local lawyers are not up to the job. Otsuka contemptuously brushes her off. A year passes. Masao has suicided in jail, his appeal having failed due to the lack of interest and competence of the local defence lawyer. Kiriko returns to Tokyo, planning revenge on Otsuka for refusing the case and causing her brother's death. Meanwhile, through the actions of a crusading young journalist, Otsuka is informed of Masao's death. His curiosity piqued, he requests the file and reviews the evidence. Otsuka also has an adoring mistress who owns a bar. By coincidence (?), the real murderer is an associate of one of her employees. Kiriko, now working as a hostess in a different bar, is asked by a friend to tail her boyfriend, whom she suspects of cheating. The boyfriend is murdered in the bar owner's flat, and Kiriko grabs the chance to set her revenge plan into action. Kiriko rigs the crime scene to falsely incriminate the bar owner, who is subsequently jailed. Otsuka's mistress out of the way, Kiriko sets out to seduce and entrap Otsuka, against the advice of the crusading journalist.