Spanish director Julio Medem's fifth film, Sex and Lucí, is a passionate and frequently erotic tale on love, loss, sex and fantasy. The story follows its main character, Lucí, on her quest to the truth behind the tragic death of her boyfriend, the novelist Lorenzo. The movie starts with Lucí receiving the phone call telling her of Lorenzo's accident, which leads her to retreat from Madrid to a quite, secluded Mediterranean island. Lorenzo had spent time on this beautiful sun-bleached island before he met Lucí, yet, for an unknown reason he had always refused to take her there. On the island she discovers the labyrinthine life of her lover through the pages of his novel. His writings reveal the tale of a one-night stand years earlier with Elena, who runs the boarding house Lucí stays at and who furthermore gave birth to a daughter, Luna, after her sexual encounter with Lorenzo. A fact which was unknown to Lorenzo up till a couple of months prior to his accident. .
Numerous flashbacks take the story back and forth in time revealing the course of Lucí and Lorenzo's relationship. Lucí, a waitress, expresses her love for Lorenzo and his work during their first encounter, which leads to some erotic scenes leaving absolutely nothing to the viewer's imagination. Hence the word sex' in the title of the movie. As the story continues the problems between the two lovers and soul mates build up. Packed with passion and love Lucí fights for what she believes, and the tormented Lorenzo discovers what he never had. Along with periods of writer's block, he becomes involved with a girl named Belen, who apparently takes care of his long lost daughter. In the meanwhile he withdraws from Lucí losing every control on his relationship. She is determined though to search for the key to her partner's happiness. This triangle with the three main female characters in the movie, Lucí, Elena and Belen, shows the magnetic power of sex and its effect on almost everyone in one way or another.