The Quest (1976)

Eight years ago, Cheyenne Indians attacked the Baudine Family wagon and captured Morgan (Kurt Russell), whom they renamed Two Persons. Now Two Persons, raised in the ways of the Indians, has been reunited with his brother Quentin (Tim Matheson), a doctor and a stranger to frontier ways. Together the brothers set out in search of their sister Patricia, who was also captured and who Two Persons believes is still alive.