The Mountain of the Sun - S1.E28

While delivering a prize bull to New Mexico, the Virginian meets a young woman, Kathy (Dolores Hart), and two older companions, whom he learns are missionaries who want to travel to Mexico to minister to the Yaqui Indians. He later learns they had hired a dishonest guide who plans to rob them so he sets off in pursuit and manages to save them. However, they refuse to give up their quest to the Yaqui's who it turns out had murdered their husbands the year before. He accompanies them on their quest and along the way finds himself falling in love with Kathy.