Carmen (Natalia Verbeke), a young Spanish woman who is engaged to be married, has her hen night at a French restaurant in London. She is invited to participate in the observance of an old custom which allows her to kiss the stranger of her choice before the marriage, symbolically "kissing her single life goodbye" and bringing luck for the future. The man she chooses is Kit (Gael García Bernal) and both enjoy the kiss far more than they have intended. They fall in love, which creates a "love triangle" among Carmen, her fiancé Barnaby (James D'Arcy), and Kit. What initially appears to be a typical urban love story begins to take some surprising and dark twists. In the third act, it is revealed that the circumstances have been arranged in order to create an "emotional snuff film." Unbeknownst to Carmen, she has been cast as the female lead in this endeavor. Barnaby has hired Kit to play a part in the deception, but has misled him by neglecting to mention that he himself, the director, will take on the role of Carmen's fiancé (Kit believing that the couple know nothing of his film). Barnaby is apparently unscrupulous, as he actually marries Carmen for the sake of the film and later fakes a violent suicide (his motive being that Carmen will never love him as she does Kit). In a state of shock, she returns to Kit, who is also horrified, guilty, and never having met the husband, still in the dark as to the true identity of a man he knows only as "Ford." He admits to Carmen that he has been paid by a man to seduce her for his film, and that he regrets it immensely. While Carmen is still there, Barnaby, whom Kit recognizes as his employer, suddenly appears, offering Kit his final pay and removing camera equipment he previously has concealed in the actor's bedsit without his knowledge. With contemptible satisfaction, he unravels his entire plan to the shocked, broken pair and bitterly ridicules them before leaving. Several months later, as the film is about to open, Barnaby appears to have won Carmen back. For a ceremony during which he is to accept a filmmakers' award, he engineers a publicity stunt by which it appears that Kit will have the ultimate revenge. However, Carmen takes advantage of the opportunity to do in her manipulative husband for real while framing his business partners for murder. Tragedy generates sensation and, while its clueless producers (Tom Hardy and Charlie Cox) await trial, the film enjoys a big opening at which Carmen and Kit arrive in style, together.