S1·E10 Episode 10

Yong realizes he has lost the ornament that belonged to his mother during the raid at the palace. Bong Soon sees him looking for it and realizes that he is the young boy who saved her when she was little. The noblemen hold a meeting for the Cheonwoo club and Yong decides to infiltrate, disguised as one of the men to look for the sword. He nearly gets caught but manages to escape. After seeing the list of the Cheonwoo club members at Lord Byun's place, he deduces that the one who killed this father was also a member of the club. Yong's parents go to the Castor Oil gang...