Jim Preston (Anthony Quayle) has been married to Amy (Yvonne Mitchell) for 20 years. They have a teenage son named Brian (Andrew Ray), a house in London and a dog. They seem perfectly happy -- except Jim is secretly having an affair with co-worker Georgie (Sylvia Syms). Desirous of something more than stolen evenings, Georgie threatens to reveal the affair unless Jim divorces Amy and marries her instead. Jim is forced to choose between his family and his fantasy.