Gervasio Robles, better known as El Pantera, is a man who lives in the slums of Mexico City. He is attacked along with his fiancee Rosaura by 2 criminals nicknamed "El Mandril" and "El Tereso", who murder Rosaura. El Pantera is unjustly accused of the murder and is locked up for 5 years in prison, where one of the inmates, nicknamed "El Indio" decides to train him, teaching him martial arts and combat tricks, since he has been chosen by General Ayala, boss of public security, to become the new guardian of the city.