After receiving the imperial edict of becoming the fiancée of the crown prince, who is rumored to have lost her sanity, Eunrin is locked up in the Northern Palace, the darkest and most remote corner of the imperial palace. Resigned to death, she decides to follow the feelings she has towards Doha... "Since you have become a woman because of me, make me become a man, my lady." A romantic and secret love story blossoms in the depths of the imperial palace, between Doha, the crown prince who hides his identity, and Eunrin, a disgraced noblewoman.