When we meet Lars (Mikael Persbrandt) and Susanna (Lena Endre) the couple has been married for twenty years. They love each other dearly and together they have created a secure, happy existence with well-paid job, a big house, two cars and a daughter who will soon leave home. Equally happy and comfortable life has evolved for Susanna's best friend Ann (Maria Lundqvist) and her husband Ulf (Jakob Eklund), also they can look forward to soon celebrate its twenty-year anniversary. During one of their parmiddagar says Susanna a story of a colleague who had been unfaithful. The history of his infidelity provoking reactions that give rise to a violent marital settlement between the two pairs.