When inept bandits the Simes Brothers kill his sister during a stagecoach robbery, gunfighter Ben Lattimore vows vengeance. When he learns that an old lawman has captured them, he considers shooting them but then decides to ride along to prevent rescue by their fellow gang members, who are still on the loose. But neither Ben nor lawman Jethro Karnin are aware that Ma Simes is also a passenger on the stagecoach . . .