A series of murders during the reign of King Sejong leads investigator Kang Chae Yoon to discover a grand conspiracy involving a group of geniuses willing to risk their lives for a cause.

A series of murders occurred during the reign of King Sejong. As Kang Chae Yoon who is investigating these cases gets closer to the root of the truth, he finds himself embroiled in a massive conspiracy behind the serial killings which involves a group of geniuses who are willing to risk their lives for their cause/goals, and secret powers who will interfere with the course of his investigations.—KBS World