An Apsaalooka (Crow) Indian girl has lived her life as a despised loner, overshadowed by her dead twin brother, who, it was prophesied at their birth, would become a "Great One" among his people.

One night, she sets off on a forbidden journey to prove to her village, and her brother's spirit, that she is the one destined to become the true Great One.

Her trek over the plains and into the mysterious region of modern-day Yellowstone National Park is a disaster, culminating in her eventual capture by a tribe of Pawnee.

Strangely, these foreigners treat her with an unfamiliar respect, and the girl starts to let down her guard.

But when it is suddenly revealed that she has been kept alive in order to be killed in a ritual harvest-season sacrifice, the girl is thrown back into her desperate battle for survival.