
1859. American settlers arrive in the San Pedro Valley to build the town of Horizon. However, a group of particularly aggressive Apache Indians living in the area are unwilling to give up their land to the Palefaces. They routinely kill all uninvited guests, including women and children, and burn the settlements. At the same time, in Montana Territory, a woman shoots a man, takes a small child and goes on the run. The sons of the victim are sent in pursuit of the fugitive. Later, in Wyoming Territory, horse trader Hayes Allison is unwittingly drawn into the story of the same woman, accidentally running into one of her pursuers.