Lee Gun prevents Dosung from taking Myung Yoon away. She leaves to treat Oh wol’s wounds and the two brothers banter, mostly Dosung who accuses Lee Gun’s grandfather of trying to kill Myung Yoon . He plans to spare Lord Choi once he’s crown prince and protect everyone he loves but Lee Gun is against it. Lee Gun says he cares for Myung yoon and would protect her but Dosung orders Myung Yoon to return home which she refuses because she plans to resuscitate the king. Dosung doesn’t believe her plan will work and wants her to go home after a day or he would tell her father where she is. He then storms off in a rage.
Lee Gun and Myung yoon talk. Lee Gun asks if his grandfather truly wanted to assassinate her. She admits it, saying she understands his reluctance to accept her being by his side. She mentions she feels hurt that he is keeping something very important from her and Lee Gun reveals that if Dosung becomes crown prince, his grandfather will kill the king. He cannot tell Dosung because he would be disappointed so he would rather prefer to keep it to himself and be labeled a bad brother. Myung yoon is fascinated by his love for Dosung and states how lucky he is to have such a brother who loves him.
Lee Gun reprimands his grandfather for attempting to assassinate Myung Yoon. Master Moonhyung only wanted the guards to kick her out, not kill her. Still, he doesn’t regret his decisions and is ready to do whatever it takes to stop their relationship. This causes Lee Gun to ask him to return to his home town and that he will take care of things himself.
Meanwhile, when Queen Dowager and Lord Choi meet, she expresses her regret for restoring their relationship and causing so much mess but Lord Choi embraces her, telling her not to blame herself. While Dosung is bothered by the relationship between Lee Gun and Myung Yoon, the other two are deep in research, looking for a way to cure the king.
Moo Baek gives Lord Choi a letter from Myung Yoon claiming she is in the temple. Lee Gun pays the queen dowager a visit. She’s surprised when he tells her he had a dream of her son prince Gwangchan and discovered she never held a memorial service for him. He apologizes for not holding one sooner for her and implores her to attend the service as a buddhist temple. Queen Dowager acts suspicious of him but when she leaves, she immediately decides to go. Court lady Kim requests her to seek Lord Choi’s advice reminding her of the last assasination attempt but the queen dowager is set on her mind.
Myung yoon is missing and Dosung storms into Lee Gun’s house demanding to know where he kept her but Lee Gun simply replies that she’s in a safe place but Dosung says he will find her without his help. He searches everywhere in the palace, even frightening some maids when he enters their private chambers.
Under Lee Gun’s orders, Gap Seok and Sang soo kidnap left councillor’s spy Cheol du who happens to be Dosung’s personal body guard and brings him to the queen’s chambers where he kept Myung yoon. Oh wol flirts with San soo in front of Gap seok. Myung Yoon tells Lee Gun about the journal in the queen’s chambers. She wants to sneak it out and Lee gun wants her to be careful.
Lee Gun informs Dosung about Cheol Du, his guard being his grandfather’s spy but Dosung wants his guard released, saying he trusts him. Dosung then confronts Lee Gun for his refusal to allow him to become crown prince in order to protect those close to him.He had supported him this whole time yet can’t understand why he won’t let him become crown prince. He says that Myung Yoon was his but Lee Gun shuts him up, telling him that he knows nothing. Lee Gun doesn’t want to tell him the truth but says that he only wants to cure their father and won’t let anyone stand in his way, even him. As Lee Gun leaves, Dosung shouts that he would marry Myung Yoon.
While the queen dowager, lord choi and Lee Gun are paying respects to the prince Gwangchan, Sang soo orders her maids to clean some flowers Lee Gun had gifted the queen dowager giving Myung yoon the opportunity to sneak into her chambers and get the journal, replacing it with a fake one. Thankfully, they leave before court lady Kim can discover them.
With the ingredients listed in the journal, Myung yoon and a group of maids secretly experiment with rats to find the cure. Unfortunately, there is no success.
Dosung pledges his allegiance to queen dowager and lord Choi, expressing his determination to become crown prince and marry Myung yoon. To prove himself, he reveals that the queen dowager’s maid Sun ok is a spy for Lee Gun and that Lee Gun plans to get the military stationed outside the fortress to oust them.
Dosung then breaks down the gate to the cold palace where his mother is kept. Mother and son are reunited. But when he expresses his desire to become crown prince, his mother vehemently refuses, unable to tell him the reason why. Due to this, he becomes more stubborn. He then meets his grandfather and the magistrate, finally joining them. But he makes his grandfather promise not to kill Lee Gun to which his grandfather agrees but when he and the magistrate are alone, left state councilor tells the magistrate that he will definitely kill Lee Gun.
Lee Gun decides to enlist the help of the Head Eununch. With Moo Baek’s assistance, he discovers that Lord Choi actually kidnapped the Head Eununch’s family in other to blackmail him. A certain man called Ring leader have been keeping them hostage. While searching the ring leader’s office for evidence of malpractice, the ring leader catches them and orders his men to beat them up but Lee Gun and Moo Baek easily immobilize them. The ring leader is shocked when Lee Gun reveals himself as a prince and threatens to expose his smuggling activities if he doesn’t reveal where he hid the Head Eununch’s family. After he tells him, Lee Gun has a guard take them to somewhere safe.
Meanwhile, the queen dowager uses Sun Ok to set up Master Moonhyung by making her overhear them plotting to kill the king. Sun ok then tells Gap seok who in turn tells Master Moonhyung. He is in the company of his allies plotting how to take down the queen dowager when the left councillor, the magistrate, cramp them at their hide out and accuse them of treason. They are immediately arrested,
When Lee Gun is told, he realises that they used Sun ok to set his grandfather up. He then goes to Myung Yoon and properly looks at the journal. He discovers the antidote ingredient transparently written in a way no one would know. This realization excites everyone and they immediately create the antidote. Lee Gun then give the Head Eununch letter from his father letting him know his family has been rescued,
The Head Eunuch is grateful and due to this allows him and Myung Yoon easy acess to his chambers. They give the king the antidite and immediately, he opens his eyes.
