Union soldier Maj. Towns (Rhodes Reason) asks fur trapper and Indian scout Luther "Yellowstone" Kelly (Clint Walker) to scout for the Army in Sioux territory. Kelly ventures into the area, only to be taken prisoner by the Sioux. Since Kelly saved the life of Chief Gall (John Russell) years before, the chief promises to free him if Kelly treats wounded Arapaho maiden Wahleeah (Andra Martin). Soon Kelly and the recovered Wahleeah are caught between Towns' soldiers and the vengeful Sioux.