"Let's date. For one month, intensely." Chaewon discovers that her identical twin sister, from whom she was separated as a child, has been treated poorly by her in-laws and is being forced into a divorce by her husband. In place of her sister, who is now in a coma after a traffic accident, Chaewon devises a plan to get revenge on her sister's family by pretending to be her. However, Yugeon, the man she stood up on their blind date because of her sister's accident, coincidentally discovers her plan. Yugeon, who must date Chaewon to secure his inheritance, proposes a contract relationship!