Wagon Train (1957)

S5E4 The Selena Hartnell Story

After bandits assault her wagon, Selena Hartnell hops aboard the train. She soon discloses that she’s a bounty hunter on the trail of William Barrett, a fugitive murderer. To everyone's surprise, it becomes clear that Barrett is none other than Will Cottrell, the pacifist leader among the passengers on the train.