Catherine (Ardant) and Bernard (Depardieu) are a middle-aged married couple. One day she finds out that he's been cheating on her, but he dismisses the affairs as meaningless and assures her he still loves her. Unconvinced, Catherine goes into a sex club one night and meets a beautiful prostitute named Marlene (Beart). Catherine hires Marlene, giving her the codename Nathalie, to seduce and spy on Bernard and report their meetings to her.
The film got a 2009 Hollywood remake titled Chloe, which has some drastic differences in terms of the direction the plot takes.
Nathalie... provides examples of the following tropes:
- Did They or Didn't They?: Towards the end, after Marlene admits to Catherine she was lying about sleeping with Bernard the whole time, she caresses Catherine's hair, they embrace deeply and then the scene fades to black, which may or may not mean they had sex.
- Fetish: Although she's not aware of it at the start, it quickly becomes clear that Catherine is less bothered by Bernard's cheating than she is interested in hearing the lurid details of Nathalie's encounters with him.
- Sexless Marriage: Bernard complains to Catherine that they haven't had sex in forever, which he uses as justification for why he sought out other women.
- Unproblematic Prostitution: Marlene for a prostitute is a pretty well-adjusted person with a good social life, and never gets into risky situations that threaten her well-being. She treats her job as something that pays the bills while she's training to be a beautician.
- Your Cheating Heart: Bernard being unfaithful to his wife Catherine is what kickstarts the plot, although he insists his encounters are all about sex and mean nothing to him. Midway through the film, Catherine tries sleeping with a different man herself and enjoys it.