An elaborate character study of two London couples as they engage in an ultimate game of partner swapping. Alice (Natalie Portman) is a gorgeous young runaway from New York's seedy sex industry; she soon pairs up with Dan (Jude Law), a thoughtful but unsuccessful novelist and journalist, who authors a book about her. Anna (Julia Roberts) is a quietly independent divorce and successful photographer. After Dan makes a move on her during a photo session for the book, she rejects Dan, who retaliates by tricking her into a relationship with Larry (Clive Owen), a dermatologist with the lust and manners of a soccer hooligan. The plot revolves around the infatuation of the couples for one another.