Set in the Joseon era, the Crown Princess gives birth to twins, a son and a daughter. Because twins are seen as a bad omen, the girl is ordered to be killed. To save her, a court lady secretly takes the baby out of the palace. The surviving twin, Lee Hwi, is raised as the future crown prince.
Years later, the hidden daughter, Dam I, returns to the palace as a maid. When Prince Lee Hwi dies after being mistaken for her during an incident, their mother forces Dam I to take his place to protect the throne and the family. Dam I grows up living as Lee Hwi, guarding her secret and keeping others at a distance to avoid suspicion.
As she struggles with the weight of her false identity, she meets Jung Ji Un, a noble scholar who becomes her teacher. He is warm, intelligent, and optimistic, and Dam I remembers him as her first love from years before. Despite her efforts to remain detached, she begins to develop feelings for him, creating conflict between her hidden truth and her role as crown prince.
The story follows her attempt to navigate duty, secrecy, and the growing affection that threatens the life she was forced to live.