Ruler - Master of the Mask Episode 39

Kim Yoo-jae gave how to make an antidote and tells that only the poisoned person has the efficacy of medicine and is poison to those who are not.

Dae Mok spread false news among water-deliverers that the king is trying to get rid of their jobs and provokes revolts. 

He also secretly sends out a message urging courtiers to return to him because he will give an antidote to the addicted.

Woo Bo succeeds in making the antidote.

The courtiers, who heard that Dae Mok's son gave the antidote, refuse to take it but ask for King's permission to return to Dae Mok. The king allows everyone to go back to Dae Mok if that is the way they choose to save their lives.

Ga-eun stops the people leaving, taking poppy pill and antidote in turn. She lost her and fell right after, and people quickened to leave the palace. 

People go to Dae Mok. Dae Mok says he will give an antidote to anyone who kneels down to him first. But oddly the spots on their bodies disappeared.

In fact, when they were going out of the palace, Ga-eun woke up and proved the efficacy of the antidote.

The King promises that the Pyunsoo group will collapse today, but that anyone who surrenders in time will save their life.

This causes many to return to the side of the king, and the king's soldiers are in a final battle with Pyunsoo's last remaining soldiers.

The king penetrates Dae Mok's room. The King says Kim Woo-jae has asked for saving his father's life and apologizes for the fact that his sin is heavy, but the incompetent country has created Dae Mok.

However, Dae Mok is already poisoned. He throws blood and meets death.

The king, who returned to the palace, said that everyone lived because of Ga-eun, and met Lee Sun at night and offered the antidote.