This exceptional psychological thriller from South Korea poses dark questions about the complex relationship between mothers and daughters. Swimming instructor Young-eun (Kwak Sun-young) is disturbed and embarrassed by the increasingly violent behaviour of her seven-year-old daughter So-hyun. When Young-eun realises that she cannot change her daughter's disposition she decides to take matters into her own hands with bloody results. Co-directors Kim Yeo-Jung and Lee Jung-chan show a mastery of suspense in these eerie scenes before they produce their biggest shock when the action jumps forward two decades and new characters emerge. Min (K-Pop superstar Kwon Yu-ri) and Hae-yeong (Lee Sul) are flatmates with their own devastating psychological family traumas, and dark secrets being to emerge keeping the audience guessing to the end.