When a rash of shocking raids threatens the hope for peace on the Bozeman Trail, Josey and Annabelle ride into the fray to seek an accord with the rising Sioux leader Crazy Horse. The wary Sioux pose but one threat; also lurking is a gunfighter who blames Josey for the death of his son in the war, and a scientist whose views of human origins are as disturbing as his hulking henchman and army of mercenaries. All forces converge in a bloody, fiery climax, where Josey and Annabelle will need more than their fast-firing rifles to protect those they love and solve a mystery that threatens to betray all their efforts.