In 1825, English big game hunter John Morgan (Richard Harris) is captured and enslaved by a Sioux tribe, forced to labor for tribal matriarch Buffalo Cow Head (Judith Anderson) as a common pack animal. Slowly, with the help of fellow slave Batise (Jean Gascon), Morgan learns his captors' language, and then proves his bravery in a battle with a neighboring tribe, earning their respect. Losing his associations with his previous life as a British aristocrat, Morgan becomes one with the Sioux.