The King falls gravely ill after having a meal with a poisoned yellow croaker. The Crown Prince is arrested for providing the poisoned fish and put behind bars. Myung Yoon sees the Crown Prince being taken away, so she goes to Prince Dosung to ask why. Meanwhile, the Left State Councillor and the Queen Dowager carry out their plan to replace the Crown Prince with Prince Dosung in earnest.

Prince Dosung uses Magistrate Yoon to help the Crown Prince escape the prison. The Queen Dowager announces that she will install Prince Dosung as Crown Prince and proceed with the wedding preparation for him and the prospective Crown Princess. However, the royal seal goes missing, putting a stop to everything they planned.

Myung Yoon decides to stay with the Crown Prince until he safely makes it out of the Capital. But Myung Yoon suddenly falls ill, which forces them to visit a nearby physician. However, the physician notices who they are and calls the government officials to catch them. Meanwhile, the Left State Council suggests forging the royal seal to install Prince Dosung as Crown Prince.