Against a Crooked Sky (1975)

The eldest daughter of a pioneer family is kidnapped by a mysterious Native American tribe and the eldest son pursues. In order to win back his sister's freedom, he must sacrifice his own life by passing the test of "Crooked Sky" and shield his sister from an executioner's arrow. Along the way, he recruits a broken down, drunk prospector to help him track down the unknown tribe and rescue his sister.