At the age of 20, Francesca Hernández is as skillful at riding, shooting, and fencing as any man. At the ancestral Hernández ranch in South America, her grandfather, Don Francisco, is suffering from the depredations of his old enemies, the Oliveros family, and believing his grandchild to be a boy, he calls for "his" aid. Francesca responds, and, when apprised of the situation, dons the costume of a caballero, and through a series of sensational episodes recoups the family fortune. Meanwhile, Roger Oliveros returns from Europe, unaware of his cousin Ramón's scheming and banditry, and falls in love with Francesca (out of disguise). She routs Ramón in a duel and is later forced to fight the man she loves. Ramón leads an attack on the ranch; Roger does not recognize Francesca until he has wounded her, and as a result, the feud is ended.