Paul (Edouard Dermithe) is a student at a prep school. One day when all the students are having a snowball fight in the courtyard, his buddy Dargelos (Renee Cosima, dressed as a boy) makes the rather reckless decision to wrap a rock in snow and throw it at Paul. Paul suffers a few broken ribs and is sent home to recuperate. He comes under the care of his sister Elisabeth (Nicole Stefane), which is when their unnaturally close and super-creepy relationship is revealed. They live in the same room, they have no nudity taboo, she calls him "darling", they play weird secret games...and for that matter Paul doesn't seem to be that seriously injured, but he stays at home in the close company of his sister.
Paul and Elisabeth are joined by Paul's good friend Gerard, who starts spending a lot of time with them. Meanwhile, with their mother having recently died and Paul content to spend every day lounging in bed, Elisabeth gets a job as a model in a clothing store. There she meets fellow model Agathe (Renee Cosima, not dressed as a boy), who moves into their spare room. Paul and Agathe are immediately attracted to each other—and Elisabeth isn't happy about it.
- And Starring: Not only does Roger Gaillard (Gerard's uncle) get an "Et Roger Gaillard" credit after all the cast members, his name is shown in a box.
- Anguished Declaration of Love: Paul is so anguished about his love for Agathe that he elects to mail her a letter to tell her, despite the fact that they are both living in the same house. But since he's an absolute moron he writes his own name on the envelope instead of hers, unleashing a series of disasters.
- Crosscast Role: Renee Cosima plays both Dargelos the rebellious teen boy and Agathe the hot model. It seems to be symbolic of the gender blending and decidedly unconventional sexuality going on; Paul is obviously attracted to Dargelos as well as Agathe.
- Diabolus ex Machina
- Paul's idiocy in writing a love letter to Agathe but putting his own name on the envelope by mistake causes her to not find out about his feelings, but does allow Elisabeth to find out, leading her to manipulate events to keep them apart.
- Pretty good timing of Paul's schoolboy friend Dargelos to send him a deadly poison, just for fun.
- Driven to Suicide: Paul, having lost Agathe, poisons himself. Seeing this, and seeming simply to ruin the last-second reconciliation between Agathe and a dying Paul, Elisabeth shoots herself in the head.
- For the Evulz: One sequence has Paul, Elisabeth, and Gerard shoplifting just for kicks. They are explicitly forbidden by the rules of their own game to steal anything that's useful or valuable.
- Gratuitous English: The whole movie is in French, except for the song that Michael sings for Elisabeth, which is in English.
- Incest Subtext: It's clear that something is very strange about Elisabeth and Paul's relationship. Unnatural closeness. Lack of any inhibition about undressing in front of each other. When Paul's sleeping after first coming home Elisabeth puts her hand on his chest and calls him "darling". Then there's the scene where the tub has been filled but they're arguing over who will take the bath. They both dive into the bathroom, and the bathroom door shuts. After a few beats, Gerard and his uncle see spilled water leaking out from under the door.
- Mood Whiplash: Wacky horseplay between Paul and Elisabeth is interrupted by news that their mother has died.
- Narrator: Jean Cocteau narrates the movie, providing exposition about the odd relationship between the siblings.
- Revealing Hug: Elisabeth puts on a mask of reassurance when Agathe tells her that Agathe is in love with Paul. But as she embraces Agathe, Elisabeth's face glowers with rage.
- Sleepwalking: Paul sleepwalks in the stereotypical movie where you stare with blank eyes. Elisabeth gets oddly excited about this.
- Shout-Out to Shakespeare: Elisabeth's Inner Monologue quote about how "All the perfumes of Arabia will not sweeten this little hand", as delivered (in French of course) by Cocteau the narrator, is a line from Macbeth.
- Snowball Fight: The plot-triggering moment comes when Paul is injured in a snowball fight and has to come home from prep school.
- Stocking Filler: Agathe's first scene has her in the changing room at the store, adjusting her stockings, garter belt and all.
- Widow's Weeds: Elisabeth puts on the whole black dress and veil ensemble after her very brief message ends with her husband being killed in a car wreck, but for her, it seems like more of a fashion statement.Agathe: It's awful to say, but mourning becomes you.