Episode 12 of "Perfect Crown" commences with His Majesty the King's announcement that the first order of business upon his ascension will be discussing the abolition of the monarchy. Understandably, everyone, including Choi-hyun and Hui-ju, is concerned about how this will unfold. It transpires that the King has already informed her of his plan, and she supports and comprehends his decision.
However, Hui-ju realizes that the royal family and the cabinet will not support the abolition. The only leverage the King has is public sentiment, and Jeong-woo is doing his best to evade the public survey the King desires. Frustrated by the King's intentions, Jeong-woo cuts off financial support to the palace. However, Hui-ju steps forward and offers to pay the pending palace bills until they figure things out. In retaliation, Jeong-woo orders an investigation into the Castle group's finances. Hyeon-guk urges Hui-ju not to fall into Jeong-woo's trap, and Tae-joo offers to attend the summoning on her behalf. He later subtly hints to the media that the cabinet is abusing its power to pressure the King.
Her family's move to support her surprises her, but she later confides in her husband that she likes it. She asks him to also stand his ground. Does Jeong-woo's treachery get discovered?
It so happens that Yi-rang visits her dad in prison to officially cut ties with him. After learning that Yi-yoon knew about her crimes, she decides to be a better parent. On her way out, Sung-won reveals that Jeong-woo knew about the gas explosion and helped lure Prince Yi-an.
At the prison, Yi-rang finds Jeong-woo waiting for her. He offers to escort her home. On the ride, he asks her to object to the King's wish to abolish the monarchy during the meeting with the royal family. She asks what will happen if she doesn't, and he threatens to ruin her and Yi-yoon by revealing that she hid a royal decree to put her son on the throne. If the truth comes out, she and Yi-yoon will be labeled as criminals. She asks him about his role in the explosion, and he admits that he tried to kill Prince Yi-an and that he won't stop.
Although the King opts not to ask for Yi-rang's help, Hui-ju does. Yi-rang comes clean and plays the recording she took during her drive with Jeong-woo. Hui-ju is hurt after finally confirming her suspicions. Yi-rang advises her to be the one to confront Jeong-woo because it would hurt him more.
During a meeting with the royal family, the King lectures them on the real reason they are against the abolition of the monarchy. Jeong-woo explains that the crown means more than just financial gain. Hui-ju interrupts the meeting and confronts him for attempting to kill her husband. She plays the recording Yi-rang gave her. A few members try to defend Jeong-woo, but the King warns them that they will be considered accomplices. Privately, Jeong-woo admits that he tried to kill Prince Yi-an because he refused to let Hui-ju go. He audaciously tries to blame the King for how things turned out. The King clarifies that Hui-ju was never his to begin with, so how could he have taken her from Jeong-woo? He leaves just as Choi-hyun arrives with the police to arrest Jeong-woo. Of course, the King is hurt by Jeong-woo's betrayal, and Hui-ju comforts him.
Is the monarchy abolished? With Jeong-woo's departure, the king decides to conduct a public survey. The people vote to end the monarchy, and the king honors their wishes. He puts everything in place and finally abolishes the monarchy. After this, he is no longer recognized as the king but simply as Lee Yi-an.
What happens after the abolition of the monarchy? Well, Yi-an takes care of everything necessary that comes with the abolition. Meanwhile, Choi-hyun and Hye-jung, who started dating even before the abolition, get married.
Three years after the monarchy is abolished, Hui-ju returns to work at Castle Beauty. Tae-joo asks her to take over Castle Card since Da-young is pregnant and he is going on his paternity leave. Hui-ju secretly enjoys her brother relying on her. She is also shocked when her dad promises to be more supportive moving forward. He promises to help her with the succession as long as she proves herself. He also claims that he never meant for her to lose; he just wanted her to stop fighting with everyone.
Yi-an spends his days with Choi-hyun, trying new things to find out what he is good at. Although Hui-ju is busy, they remain happy, and he is supportive of her. He also starts wondering about whether he should propose again and get a wedding ring. He is offended when Hui-ju asks why they should bother. Anyway, the couple remain deeply in love. He later admits that he fell for her back when they first met in school.
As for Yi-rang, she happily enjoys being a present mom for Yi-yoon as he tries to discover his new hobbies. She is intent on making him a musician, and Yi-an buys Yi-hoon a violin.
How does Perfect Crown end? Yi-an visits the royal exhibition and feels relieved after giving it all up. Hui-ju is late, but he doesn't mind. The show ends with them happily attending a baseball game and kissing when the kissing cam pans to them. It's all good since they don't have to maintain decorum and can speed up things as much as they want to now!
