Based on actual events that took place at Gwangju Inhwa School for the hearing-impaired, where young deaf students were the victims of repeated sexual assaults by faculty members over a period of five years in the early 2000s.

A sickly girl Ju-ran transfers to a new sanitorium boarding school to regain health. But she discovers that students are disappearing and notices abnormal changes happening to her body. She suspects the school for what's happening and tries to discover what secret is hidden.