Dal Moon's men are investigating into the human trafficking case by Qing. The new courtesan house emerges as their target as it is owned by someone from Qing. A murder occurs of a nobleman and Min Jin Heon and the Saheonbu are both investigating it. Yeo Ji finds out the courtesan house is where the deals take place for selling and buying girls. Prince Yeoning senses danger and goes after Yeo Ji.

Jipyeong Oh is murdered and Prince Yeoning is witnessed to be the murderer and it arrested by Saheonbu. He is investigated by Saheonbu but is not willing to speak the truth. Meanwhile, behind the murder cases are what is known as master-murderers and the murderer of Jipyeong Oh turns out to be a little girl wearing a tattoo. Moon Soo and Yeo Ji investigate what's behind the murder cases.

Saheonbu threatens to resign all its members unless right to investigate the murder case involving Prince Yeoning is given to them. The king calls Prince Yeoning and asks him to tell him everything that he knows about the recent incidents. When he does, the king is deeply moved and decides to give Prince Yeoning three days to prove himself innocent. The investigation of the murders lead to human trafficking deals with Qing and to the courtesan house.