Paradise Hills is set in an undetermined future where society is divided into two sub-types: the upper-class or "Uppers", and the mid- and lower-class, named "Lowers".
Uma, a privileged young woman, is against marrying another Upper, Son, and instead falls in love with a working-class young man named Markus. As a result, she is sent to Paradise Hills, a school for young ladies located on a remote island in the middle of the ocean.
Upon waking up in Paradise without knowing how she arrived there, Uma meets other students like Amarna, a pop-star sent after singing her own songs against her record company's will; Chloe, a plus-sized young lady whose parents want her thin and compliant; and Yu, a Lower sent there for refusing to inherit the family business.
Uma encounters the eccentric Duchess, headmistress of Paradise Hills, who tries to convince her to marry up as her mother wishes. Uma suspects a hidden purpose behind the facility's luxuries, as the daily sessions of make-up, hairdressing, etiquette, and therapy do not seem to be working on her classmates.
As Uma and Amarna plan to escape, Uma is shocked to see Markus as part of Paradise Hills' staff. Amarna, who had developed feelings for Uma, feels bitter about this. When Amarna alerts Uma about the sleep-inducing substance in their dinners, Uma investigates and discovers the chilling truth: the island is a control room to analyze the students' behavior and appearance for replication by Lower women hired to replace the Uppers after their deaths.
With time running out, Uma and her friends must find a way to survive before they become the next targets.