In-ho Kang is a newly appointed teacher at a school for the hearing-impaired in Mujin city. While teaching the hearing-impaired students, In-ho feels something strange about the kid's distant appearances. He found that the children are being physically and sexually abused by their teachers. When he decides to fight for the children's rights and expose the crimes being committed at the school, In-ho teams up with human rights activist Yoo-jin Seo. But he and Yoo-jin soon realize the school's principal and teachers, even the police, prosecutors and churches in the community are actually trying to cover up the truth.
