A young woman named Eugenie is swept into a disturbing world when her stepfather, an eccentric writer, invites her to spend the weekend on an isolated island. There, she is introduced to a libertine circle, presided over by a wealthy and enigmatic woman named Madame Saint Ange. Eugenie is both intrigued and confused by the hedonistic lifestyle and strange rituals she witnesses. The group engages in storytelling that blurs the line between fantasy and reality, often dipping into the erotic and the taboo.

As Eugenie becomes more deeply entangled in the group's games, she discovers that her stepfather has ulterior motives for bringing her to the island. The gatherings grow increasingly bizarre, featuring depraved acts disguised as 'ceremonies' and focused around the writings of the Marquis de Sade. She is forced to question everything she knew about desire, freedom, and morality, while her own sense of self is slowly eroded by the seductive yet dangerous atmosphere. Caught in a web of manipulation and seduction, Eugenie must navigate her awakening sexuality and the dark intentions of those around her.