Married London couple Ellie and Alvin have seen the lust fade from their marriage several years after their wedding. They act more like friends than husband and wife. They have little in common; she is a clothing designer, eager to conquer the fashion world and make a name for herself, while he seems content with being with his friends and maintaining a low profile in his office. She is also willing to try new things in their sex life, including bringing in new partners, while he is comfortable with keeping their physical relationship low-key. After their friend Peter admits that he cheated on his wife Janet, they are determined to spice up their marriage and re-ignite the sparks they once felt towards each other. After debating what they can do to save their marriage, Ellie suggests that they "swing," and have consensual affairs. They find the ideal couple, Richard and Clementine, who have similar interests and the same marital problems as them. After their night with them, they debate whether or not swinging actually helped revive their relationship.