In 1936, under the war clouds over the Manchurian border, 60-year-old Shozaburo Oshima is concerned about the future of his only son, Ryuji, who has refused to follow in the footsteps of his gambler father and decided to become a doctor. Ryuji leaves home to work at a clinic at a dam construction site where he finds the treatment of the laborers intolerable. But when he challenges the boss, who thinks nothing of murder, he discovers to his astonishment that he is safe because of his father's reputation. Torn between filial piety and his ideals, Ryuji is told of the murder of his father by men of a rival gang. He experiences another shock when informed that the woman behind the rival gang is his true mother who was forced to leave his father due to an unwritten code among gamblers.
Ryuji Oshima, a gambler, kills Saiga in self-defense, and considering himself unfit to lead men, secludes himself in a temple to atone for his misdeeds. At home, when his mother, the boss of a construction gang, bids for and gets the job of building the Town Hall, other gangs set out to disrupt her business and try to kill her.
A noir action whodunit with Kobayashi his usual jaunty self as the smart aleck private eye whose missing person search soon becomes a murder case. Nightclub-managing, drug-dealing gangster Uchida is the prime suspect in the case until he commits suicide. Kobayashi then discovers evidence that points to the doctor sibling of an innocent girl. The climax in a rural snowy locale is suspenseful and well-staged.
