Rosie, a bookworm, hates her life. She goes to an elite and nightmarish unified education institution where she lives with a beastly roommate. Her only escape is the establishment's underground with its bizarre creatures and surreal experiences.

Then, Thomasin enrolls. Rosie observes Thomasin from afar. Obsession blooms. She changes her behavior to match Thomasin's-her ferocity, her indulgences, her lewdness. When Thomasin rises into a pop star, Rosie becomes a fanatic. But to be like Thomasin is not enough. Rosie must become Thomasin.