While flying to Lisbon, Portugal, to give a lecture, a writer and magazine editor, Pierre Lachenay (Jean Desailly), encounters an attractive flight attendant, Nicole (Françoise Dorléac), and winds up spending the night with her. What was intended to be a one-night stand becomes a tumultuous extramarital affair once he gets back to Paris and his wife (Nelly Benedetti) and kids. Pierre tries to keep the affair secret, but, when his wife suspects him, she snaps.