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.