The Rifleman S01E04 - The Marshal

Micah Torrance, formerly a famous Marshal, but now a drunken derelict with a crippled arm from a gunfight, turns up in North Folk and is taken on as a hired hand by Lucas McCain, who wants to give the man a chance to rehabilitate himself. His good deed backfires when three outlaws ride into town bent on avenging themselves for past troubles with Micah. The outlaws kill the local sheriff, leaving Lucas and Micah to protect the town alone.