The story follows Catherine Weldon (Jessica Chastain), who moved from Brooklyn to the Standing Rock Reservation in Dakota Territory to help Sioux chieftain Sitting Bull keep the land for his people. Weldon wrote letters to the federal government on behalf of Sitting Bull and lived on the land for several years with her son. Written by Dik Nolan

The year is 1845, the earliest days of the Oregon Trail, and a wagon team of three families has hired the mountain man Stephen Meek to guide them over the Cascade Mountains. Claiming to know a short cut, Meek leads the group on an unmarked path across the high plain desert, only to become lost in the dry rock and sage. Over the coming days, the emigrants must face the scourges of hunger, thirst and their own lack of faith in each other's instincts for survival. When a Native American wanderer...