For me, who must protect the Empress, emotions are useless, yet a single day's connection has made me this way. What should I do when feelings grow stronger? Ilang, the leader of the secret guard 'Amsubi' that secretly protects the Empress. Due to an unexpected incident, he becomes connected with the courtesan Hwasol, and a 'love letter' arrives for him, which must not be revealed. However, before he can even worry about it, Yoon, the daughter of the Left Minister who seeks to bring down the Empress, finally enters the palace. The struggle between Ilang, who wants to protect the Empress, and the Left Minister, who wants to bring her down, deepens their connection!