At the story's opening, Williams's cavalry unit has one assignment: kill Apaches in the "faraway blue" mountains of southwestern New Mexico Territory, also known as the Black Range. As a fighter in the white man's campaign to obliterate the Indians and take over their lands, Williams finds a nemesis in Nana, an old Warm Springs Apache warrior who is a tactical genius. Nana leads his small band of followers to repeatedly strike area mining camps and settlements. Both men know they must meet before the end of the war and a maddening cat-and-mouse pursuit ensues.
Williams is sustained by his love for Sheela Jones, a mulatto whom he wants to marry when the army will allow it. But Sheela's love for Moses guides her to take an immense risk just as Moses and Nana ride out to settle their score.