Set during the 19th-century Joseon Dynasty, the story follows Hong Ra-on, a young woman who disguises herself as a man and makes a living as a relationship counselor, offering advice to men on how to woo women. Through a series of events, she is sold into the palace as a eunuch and finds herself serving the Crown Prince, Lee Yeong, who is unaware of her true gender. As they navigate the treacherous political landscape of the royal court, their relationship evolves from a master-servant dynamic into a deep, forbidden romance. As the Crown Prince struggles to assert his authority against corrupt officials and his own father, he finds solace and strength in Ra-on. However, their love is threatened by the rigid social hierarchies of the era, the discovery of Ra-on's identity, and the dark secrets surrounding the history of their families. The series explores themes of identity, loyalty, and the pursuit of love against the backdrop of palace intrigue and historical upheaval.