Titled after the name of a little girl's dress size, the coming-of-age drama 36 Fillette follows a couple days in the life of 14-year-old Lili (Delphine Zentout), whose physically mature features contrast with her immature adolescent angst.
Away from her home in Paris, she is painfully bored during a summer vacation in a windy little campground near the resort town of Biarritz. She's stuck with her emotionally unavailable parents (Adrienne Bonnet and Jean-Francois Stevenin) and older brother J.P. (Stephane Moquet).
After some blatant begging on her part, J.P. eventually agrees to take her out to a disco. They don't have a car, so they hitch a ride from the middle-aged Maurice (Etienne Chicot), who is out cruising in his sports car. Maurice and J.P. go to a disco, but Lili is too young to get in.
She spends the evening at a café talking to the celebrity musician Boris Golovine (Jean-Pierre Leaud), but she agrees to meet Maurice for a date at midnight. After much pleading with the doorman, Lili is allowed in to the disco where she dances with Maurice.
Eventually, she leaves the club with him and spends the evening in his fancy hotel room. 36 Fillette was written and directed by Catherine Brelliat, who adapted the screenplay from her own semi-autobiographical novel.