In 1840, while California is ruled by Mexico, American settlers are in constant danger from Mexican marauders. After a band of Mexican soldiers led by American renegade George Granville kill the parents of Leonardo Davis, he vows vengeance and begins a career as a masked highwayman who terrorizes the Mexican offenders. Because Leonardo gives his plunder to those Americans who have been robbed, and he protects the women, children, poor, and helpless from attacks, he becomes known as "Captain Courtesy." At the San Fernando Mission, Leonardo falls in love with Eleanor, the orphaned ward of Father Reinaldo. For Eleanor's sake, Leonard renounces his mission of vengeance and joins the California Riflemen. When Granville learns about a cache of gold hidden at the Mission, he organizes an attack. Leonardo crashes through the stained glass window on his horse and rides to General Stephen Kearny's troops encamped in Los Angeles, who then rout the Mexicans. When Granville boldly admits that he slew the Davises, Leonardo fights him, but Eleanor persuades him to spare Granville's life.
