Paco exploits Mercedes in a cabaret and, together, they win a competition in the Salón México. Only, Paco does not pass on to her the share of the money she needs to pay for the graduation of her younger sister Beatriz at an expensive school for young ladies. After a robbery, Paco and Mercedes are put into goal. A guard tries to help Mercedes, goes to visit her sister in school, and falls in love with her. The only difficulty is that Beatriz is in love with a lieutenant in the airforce, the son of the owner of the school. Now out of prison, Mercedes agrees to her sister's wedding, but she and Paco end up killing themselves in the course of yet another argument.