Three students from Jing Mu Girls' Middle School go missing and turn up dead. Xiao Tong, a special education student with speech impairment, feels like someone is watching her. During the rehearsal for the school's foundation day event, a corpse falls from the ceiling of the auditorium, and Xiao Tong disappears in the midst of confusion. Her mother, Li Han, who has been working at the school to be close to Xiao Tong, begins her pursuit.