A nameless ronin, or samurai with no master, enters a small village in feudal Japan where two rival businessmen are struggling for control of the local gambling trade. Taking the name Sanjuro Kuwabatake, the ronin convinces both silk merchant Tazaemon and sake merchant Tokuemon to hire him as a personal bodyguard, then artfully sets in motion a full-scale gang war between the two ambitious and unscrupulous men.
In the midst of an attempt to take over his company, a powerhouse executive is hit with a huge ransom demand when his chauffeur's son is kidnapped by mistake.
Aspiring to an easy job as personal physician to a wealthy family, Noboru Yasumoto is disappointed when his first post after medical school takes him to a small country clinic under the gruff doctor Red Beard. Yasumoto rebels in numerous ways, but Red Beard proves a wise and patient teacher. He gradually introduces his student to the unglamorous side of the profession, ultimately assigning him to care for a prostitute rescued from a local brothel.
