集賢殿
Ddol-bok returns to the palace under the name of Kang Chae-yoon (Jang Hyuk) to kill the king. However, during his time there, he becomes embroiled in the mystery surrounding the deaths of several Hall of Worthies scholars. The deaths were caused by a secret society called "Hidden Root," which was created long ago by followers of Jeong Do-jeon, with the goal of giving more power to ministers and less to the king. King Taejong killed Jeong Do-jeon and all of his family except his nephew, Jeong Gi-joon, who is now the leader of Hidden Root and lives in disguise not far from King Sejong.