So-Myeong, an exemplary child who excels in her studies and manners, has always lived up to her mother's expectations of being the perfect daughter. However, when her younger brother is found dead in a river, she begins to suspect that her mother may be a killer. This sets off a chilling mother-daughter thriller as So-Myeong tries to escape from her mother's grasp while her mother attempts to eliminate any obstacles in her child's life.