Yojimbo

A masterless samurai, Sanjuro (Toshirô Mifune), wanders into a town divided by two warring clans. After displaying his formidable swordsmanship before both clans in a brawl with street thugs, Sanjuro offers his services to the highest bidder. When one clan conspires against him, the clever warrior switches his allegiance to the other side, with the ultimate goal of tricking the two equally despicable and foolish clans into exterminating each other. Sanjuro's authority is challenged, however, when Unosuke (Tatsuya Nakadai), a brother of one of the leaders, comes to town wielding a modern contraption: a gun. (official distributor synopsis)