Missing Crown Prince

The Last Option (1x11)

:

On the day of Prince Dosung’s investiture ceremony, Gun shows up with the real royal seal. He clears his name in front of everyone and finds his place in the palace again. Gun warns the Queen Dowager and Choi Sang Rok that he will carry out an interrogation to disclose who poisoned the King. Choi Sang Rok comes up with a way to save both the Queen Dowager and himself.