You disguised yourself as a man to enter the palace (you're a girl name Li Erum) because you wanted to avoid marrying into your family's choice. You manage to work in the palace as a eunuch and meet Moon Jie a cold war commander(secret, he is also a crown prince) and you don't know he is a crown prince.

John and Sherlock are your new housemates. John is a psychiatrist and Sherlock is a private detective (your job is the police). On the first day you move in, there is a mysterious murder in your apartment building.