The central character of the story is a young woman named Yoo-jin. She used to be a successful psychotherapist but decided to quit her job and dedicate all her free time to her family. Yoo-jin's daughter passed away, and she is unable to cope with the guilt she feels. Trying to compensate for her loss, Yoo-jin puts all her efforts into taking care of her husband and son. Her son is preparing to enter college, and Yoo-jin decides that he should receive tutoring. She hires a woman who is supposed to help prepare her son. But there is something off about her...