Yoo-ri, a seemingly model student from a well-to do family suddenly commits suicide. Detectives suspect suicide, but her mother Hye-young believes that Yoo-ri’s classmate Ye-na and homeroom teacher Gi-beom were the killers. As the investigation dives into the lives of these people, it spirals out of control due to conflicting statements between the three, but detectives find out that Hye-young caused cracks in Yoo-ri’s heart. Deeply believing that she was doing everything possible for her child out of love, can Hye-young uncover the truth behind her daughter’s death?