A mad doctor uses patients at his isolated psychiatric institute as subjects in his attempts to create longevity by surgically installing an artificial gland in their skulls.
Mexican gunfighter Dave Robles outdraws the town's outlaw-turned-sheriff and is invited to fill the dead man's shoes. But a tin star doesn't bring automatic respectability and Robles is shunned by the town's leading citizens. His popularity with its less-savory element, particularly saloonkeeper Bannister, wanes dramatically, too, as he starts to take his job seriously. It is his love for a decent, caring woman that keeps Dave in town, but can she convince him to lay down his gun and start a new life?
A young woman discovers she is the daughter of the infamous Dr. Jekyll, and begins to believe that she may also have a split personality, one of whom is a ruthless killer.
