10 years ago, Mi-ju lost her ambition to become a cellist when her entire family was brutally murdered. Due to the trauma, she now leads a quiet life as a teacher with her husband and children. However, dreadful events begin to occur.

Danyeon and Hyeongpil are a married couple who have been in a bad marriage for many years due to a lack of sex. One day, Danyeon learns of Hyeop-pil's affair through a phone call from a stranger, and in revenge, she has affairs with 12 different men.