Yeong Eun, a swimming instructor, lives alone with So Hyun, her 7-year-old daughter. So Hyun exhibits increasingly violent tendencies, which are spiraling out of control. 20 years later, new characters emerge: Min and Hae Yeong, who deal with cases of solitary deaths and live together. They each harbor their own personal hell. In that damp hell, the presence of the mother is ever-present.