When the King knows about Crown Prince's illness, he is furious. Jang Moo Yeol also spread the news so that officials will stop supporting Jang Ok Jeong. So, they all stop supporting her. Furthermore, she is arrested for attempting to kill Dong Yi and the prince. She wanted revenge and ask her brother to start a fire at the palace so that the assassins can sneak in to kill Dong Yi and the prince during the chaos. During the fire, the assassin sneaks in and tries to kill the prince but Dong Yi throws herself in front of her son and gets slash by the sword. (Source: Viu)