In 19th-century France, teenage Teresa lives with her cabaret-singer mother. A friend pays for Teresa's year at Ms. Fourneau's boarding school, where she discovers the school is also a prison.
The strict Ms.Fourneau has everything locked up, while her protégée, Irene, bullies the girls. Ms. Fourneau's teenage son spies on the girls and his mother devalues them.
When students start disappearing, they're suspected to be running away, but are actually killed by a serial killer. Irene learns of Teresa secretly meeting Luis and tortures her until Teresa decides to flee in the middle of the night.
