A suspicious murder case occurs during the reign of King Seongjong. Joon Kyung, the son of a concubine and a rookie judicial official of Hanseong, wishes to become an official guard and absolve his shame by solving the case. As a result of the investigation, Joon Kyung believes Seongjong's uncle, Lord Chang Won, is the criminal. Surprisingly, all express opposition when he points him out. What could be evidence to arrest the king's uncle?