A Mexican beauty replaces her toreador brother in the bull ring so he can pursue his musical career.

In a small Mexican town, famous matador Antonio Morales is teaching his students bullfighting techniques when he receives word that his wife has gone into labor at their villa. Accompanied by his assistant, Chato Vasquez, Antonio races home and arrives only minutes after his wife has given birth to a baby girl. Antonio, who had hoped for a son that he could model after himself, or mold in his own image, is deeply disappointed when he learns that his new baby is a girl. His disappointment soon turns to joy, however, when the doctor informs him that his wife has had twins, and that the second baby is a boy. After naming his son Mario and his daughter Maria, Antonio boasts to his friends that Mario will become the best matador in the world. Mario and Maria enjoy a happy childhood and grow up to become the best of friends, helping each other whenever they can. When Mario is old enough to enter the bullfighting ring, his father begins a rigorous training regimen. While Mario shows only mild interest in the sport, Maria becomes a bullfighting expert and secretly takes lessons from Chato. Mario's lack of enthusiasm for the sport is shared by his mother, who fears for her son's life and tries to protect him from his father's demands. When Mario composes a sophisticated musical suite, his mother realizes that he is a prodigy and encourages him to continue his music studies. On the day before Mario and Maria's twenty-first birthday, Maria tells her brother that she sent her fiancé, Jose "Pepe" Ortega, to Mexico City to deliver the manuscript of his suite to the famous symphony orchestra conductor Maximino Contreras. Maximino is greatly impressed by Mario's composition and travels to the Morales villa to invite Mario to study in Mexico City. Maximino arrives at the villa just as Mario is about to fight his first big bullfight. Antonio forbids Maximino from meeting Mario before the fight, and sends him away with a promise that he will tell Mario about his visit after the fight. Antonio is proud of his son's performance in the ring, but neglects to tell him about Maximino's visit. Determined to meet Mario, Maximino follows him to the town of Puebla, where the young man is set to fight his next bullfight. During the bullfight, Maximino manages to get close enough to Mario to meet him and ask him why he did not reply to his invitation. When Mario realizes that his father had deliberately kept the news of Maximino's visit a secret from him, he walks out of the bullfighting ring in anger and leaves for Mexico City. While Antonio is disgraced the following day by newspaper accounts that call Mario a coward, Maria vows to find her brother and restore her family's good name. Hoping to lure her brother back home with a publicity stunt, Maria disguises herself as Mario and fights a bullfight under his name. Maria's plan works when Mario hears about the fight and leaves Mexico City to find her. He finds Maria just as she is being attacked by a bull. Mario saves Maria from further harm by jumping into the ring, and the public's respect for the Morales family is restored. Antonio later makes amends with his son, and finally gives him his consent to study music with Maximino.