Prince Yeoning, later to be one of the most renowned monarchs of Joseon, the reformist King Yeongjo, embarks on a youthful adventure to the succession to the throne. Birth name I Geum, Prince Yeoning was born of low origins, and naturally becomes a court outsider. But he lacks no company. Park Mun Su, later to become one of the most famous amhaengeosa, or secret royal inspector, is a persistent pursuer of justice. Dal Mun, a street gang leader and a popular clown, is a master of martial arts and knows everything in and around Hanyang the capital. Yeo Ji is a damo, literally Tea Lady, who is employed as an attendant in government departments, and at times acting as detectives to investigate crimes that are considered inappropriate for male inspectors. Together, they are commited to the reform of Saheonbu, today's equivalent of the prosecutor's office, to uphold the justice of the times.