During the Apache Wars in Arizona, the new Lieutenant Colonel of a Cavalry Regiment in the southeastern part of the territory is given the job of capturing and returning to the reservation, or fighting and destroying all hostile bands of Apaches living and raiding outside of the established reservations. In being assigned this difficult mission he discovers the difficulties of accomplishing this without the help of enlisting the help of Apache Scouts. In enlisting the scouts he discovers the hostility between members of the Apache bands who have enlisted to scout for the Army and the hostiles who have left the reservation. He meets Tosay, leader of the Scouts and his adopted sister Matilde, taken as a captive by the Apaches in a raid on her families hacienda in Mexico, and learns of their hatred for two of the Apache leaders of the hostiles who are brothers and Tosay's cousins. The Colonel discovers that in trying to bring the hostiles back to the reservation, Tosay and Matilde have no intention of capturing their cousins and only want to kill the brothers and are using scouting for the Army as a way to do it. He also finds that the International Border between the United States and Mexico, where the hostiles have their strongholds, is a deterrent in bringing the hostiles to combat and defeating them. In his interactions with the scouts he finds himself attracted to Matilde and her to him which carries them and their descendants into the 20th and 21st centuries.