When Ji-won, a 37-year-old cancer patient, walks in on her husband and best friend, she realizes her whole life has been a lie. What’s worse, she dies a tragic death at the hands of her husband. Would things have been different if she had made different choices? Fortunately for Ji-won, she is given the chance to rewrite her fate when she is reincarnated as her younger self. This time, she vows to live a happy life. But first comes revenge. Her plan? To marry off her now former best friend to her lying, cheating husband.

An AI programmer accidentally develops an AI program called Cho Sang Shin, which will identify trashy humans, and she uses it to save people who are in difficult relationships.

Drama tells the story of Ko Dong-Man and Choi Ae-Ra. In their school days, Ko Dong-Man took part in taekwondo. Now, he makes a living by working as a contract employee and also goes after the UFC title. Choi Ae-Ra hoped to become an announcer, but she gave up her dream. Now, she works at the information desk of a department store.