Rosario (Palma) becomes a prostitute after losing her father and discovering her boyfriend had a liaison with another woman. In Veracruz, Rosario lives above a sordid cabaret "selling her love to the men coming from the sea." One night, sailor Alberto (Soler) rescues Rosario from the dirty hands of a drunk man. They get along and go to Rosario's room. After making love, they begin to talk and Rosario discovers they're siblings...