Renhao (Gong You), a mute art teacher from Seoul, came to Wujin to apply for a job at the Charity School for the Deaf and Dumb. Heavy fog fell and he accidentally crashed his car. While repairing it, he met Rouzhen (Jung Yumi), a member of the human rights organization. Renhao's wife died early, and his 8-year-old daughter was born with asthma and was taken care of by her grandmother, so he worked hard to find a job to support his family. However, the principal and the dean of the twins forced Renhao to ask for a bribe of 50 million won. At the same time, Renhao gradually discovered that the school was shrouded in a tense and depressing atmosphere that was suffocating. There were three children who attracted attention: the smart Jin Yandou (Kim Hyun-soo), the greedy Chen Youli (Jung In-soo), and Minsu (Baek Seung-hwan), whose younger brother committed suicide. Minsu always had bruises on his face. After class, Renhao also heard shouting and crying in the girls' bathroom, but he did not investigate further when the guard stopped him. Later. He accidentally witnessed the principal bribing the police, the instructor beating Minsu, and the dormitory supervisor drowning Yandou. A shocking secret was slowly revealed, and the truth shocked South Korea... This film is based on a real incident in a school for the deaf and mute in Gwangju in 2005, and is adapted from the novel of the same name by the Korean writer Kong Ji Young.