Yul Brynner plays the cheerfully lawless rogue "Catlow", perpetually on the run from lawman and friend "Ben" (Richard Crenna) and malevolent bounty hunter "Miller" (Leonard Nemoy - in one of his early post-Star Trek roles). Great music, obviously 'influenced' by the soundtrack to "The Magnificent Seven", and an over-the-top plot involving stealing mexican gold stolen from the confederacy, Apaches, alternatively willing and vengeful women, banditos, and enough captures and escapes for several movies. Lightweight fun (in that lightheartedly violent way of late-1960's/early 1970's movies, in which any character whose name we didn't know was liable to receive instant death from the hero or villain -- a characteristic, of course, of many action movies to this day), with just enough actual danger (from the Apaches and Miller) to keep it interesting.
