Sanjuro (Toshiro Mifune) is a Ronin, a masterless samurai, wandering 19th century Japan. Searching for work, he enters a rural hamlet with two rival family gangs struggling for control. The two sides are even matched and see Sanjuro as the additional strength each side needs to win. He craftily plays both sides against each other, causing a bidding war for his assistance. But the battle is complicated on the when Unosuke (Tatsuya Nakadai), a gangsters son, returns to town armed with a modern revolver. Now Sanjuro must somehow overcome the gunslinger and save the town from itself.