Let Them Rest (1967)

In Fort Hernandez, San Antonio, a group of Mexican villagers is betrayed by Confederate soldiers led by aristocratic Officer George Bellow Ferguson and they are slaughtered. After the massacre, the boy Requiescant wanders in the desert but is rescued by the religious Father Jeremy, who is traveling with his wife and daughter in his wagon. The boy is raised like a son, and when he grows up he is very close to his foster sister Princy. One day, the rebellious Princy leaves her family to travel with a theater company. Requiescant promises his foster parents that he'll bring Princy back home. On his journey he displays great self-protection skill with his gun. When he arrives in San Antonio, he finds that the city belongs to Ferguson. He goes to a saloon to find that Princy has become a prostitute pimped by Ferguson's henchman, gunslinger Dean Light. Requiescant asks Ferguson to release Princy to him, but the boss of the town is reluctant to release her. When Requiescant learns that he is Mexican and the fate of his family, he decides to help the priest Don Juan start an uprising against Ferguson.