The story is set during the Joseon Dynasty when twins were considered an ominous sign. When the Crown Princess Consort gives birth to twins, an order is sent to kill the daughter. To save her, she is secretly sent out of the palace.

The Crown Prince's wife gave birth to twins, but twins were considered an ominous sign. The twin daughter was supposed to be killed, but her mother begged to save her life. Secretly, the twin daughter is sent out of the palace. Years later, the twin son Lee Hwi dies, and the twin daughter is forced to take his place, becoming the Crown Prince. Because of her secret, she lives afraid her real identity will be revealed, and Lee Hwi is unable to have anyone close to her. She hides her emotions from others and she makes biting remarks. Jung Ji Woon comes from a noble family. He is handsome, smart, an optimist who enjoys life, and he becomes her tutor. Crown Prince Lee Hwi develops feeling for Jung Ji Woon, who she shares a past with.—AsianWiki