Vanni and Linda have been engaged for ten years, they live together in a penthouse in central Rome. He is a writer, she is his ghostwriter. Their best friends are Costanza and Alfredo, known as Prof. Two doctors, she is a dermatologist and he is a heart surgeon in love with his job. They are married, have no children and manage their marriage like a business company.
Costanza suddenly discovers that Prof. has a lover, and in the throes of a panic attack, she bursts into the home of Vanni and Linda. Thus begins the longest night for the four protagonists who, between quarrels, jokes, laughter and admissions of guilt, will put their loves and friendships at stake.