In 1850, in California after the signing of the Guadelupe-Hidalgo treaty with the United States, which ended the Mexican War, Mexicans fight for land guaranteed to them by the treaty. President Zachary Taylor sends Cavalry officer Captain John Carroll, his personal aide, to insure the rights of Mexican citizens after Paula Castillo recounts to him the atrocities committed by American land-grabbers, including the murder of her father. Paula and Carroll quickly fall in love, and he befriends her brother Ricardo, who, as leader of a band of Mexican guerillas, has been outlawed by the terrorists. At first the Mexicans are suspicious of Carroll, until he fends off the raiders and their leader, Harris, when they invade the Castillo hacienda during a fiesta. Ricardo and his guerillas agree to lay down their arms in favor of Carroll's plan of non-violent resistance. Harris, who controls the crooked and weak officials, has Carroll jailed on a trumped up charge, and Ricardo dies in a skirmish with the raiders while helping Carroll to escape. Carroll then decides to have the Mexicans take up their arms and leads a series of night attacks, which drive the Americans off the land they usurped. Paula, meanwhile, is kidnapped by the brigands and her hacienda is jeopardized during a gun siege, but Carroll saves Paula and her home by fighting Harris hand-to-hand. The Mexicans celebrate the restoration of their land at a large fiesta, and Carroll wins Paula's hand and the governorship of California.