Claude Chabrol describes Just Before Night as "the story of a man who kills someone, and then finds out he himself is dead". In it, he created a psychological drama which begins when Charles, the central character, strangles his blonde mistress, Laura.

Charles is a home-loving family man of about 45, head of a publicity agency in Paris, and lives in a modern home near Versailles. The house was designed by his best friend, Francois, who is Laura's husband. JIll Charles, sex with Laura has been mystic, frightening experience, contrasting sharply with the spontaneous fun he shares with his wife, Helene. During the affair, Laura dominated him completely with her bizarre desires. At their last meeting, attempting to satisfy her masochistic demands, Charles closed his hand too hard and too long around her throat. Had he done it voluntarily or was it an accident? Charles cannot decide, but his life has become a nightmare of guilt and longing for punishment.