When the crown prince is killed, his twin sister assumes the throne while trying to keep her identity and affection for her first love a royal secret.When the Crown Prince’s consort gives birth to twins, the twins are considered an ominous sign, and the order is sent to kill the daughter. To save her, she is secretly sent out of the palace. A few years later, the twin son Lee Hwi dies due to an unfortunate accident. To hide her twin son’s death, the mother brings back the daughter and raises her as Prince Lee Hwi. Lee Hwi eventually becomes a crown prince. Fearing that her real identity will be revealed, Lee Hwi is unable to have anyone close to her and hides her emotions from others, making biting remarks. Although she distances herself, she starts developing feelings for Jung Ji Woon, her teacher who comes from a noble family. Jung Ji Woon is a teacher from the Crown Prince sikangwon, a government office for the sole purpose of educating crown princes.