Prince Dosung discovers that his grandfather, the Left State Councillor, joined hands with the Queen Dowager and gets infuriated. The Crown Prince meets Prince Dosung secretly and tells him about Queen Dowager's secret affair and who her secret lover is. Meanwhile, Queen Dowager meets the Queen and asks for her help dealing with the King.

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.