Chae Gyeong is an ordinary high school student. One day, she receives some unexpected news. Because of her grandfathers will, she must marry the unendurable Crown Prince Lee Shin who also attends her high school. Chae Gyeong resists the proposal but reluctantly marries him to help her debt-ridden family. As she struggles to adapt herself to the proper manners and royal duties of palace life and to her disagreeable husband, Lee Shin's sentimental cousin and second-in-line to the throne, Yul, steps into her life. She feels like she can rely on Yul to help her, but finds it difficult not to worry about her haughty, cold-hearted husband. To help bridge this gap, the senior members of the royal family take some special measures to get them to spend the night together.
In the 14th year of Inhwa dynasty when the Hyun emperor’s illness gets worse than ever, the empress commands the Crown Prince, still in high school, to marry the bride who has been arranged for him beforehand. However Prince Shin, proposes to his secret lover, Hyo-rin Min, an ambitious ballet student who takes his proposal as a joke and turns him down saying that her success as a ballerina is of her primary concern. Meanwhile, the family of Chae-kyeong, an ordinary high school student, is in deep financial trouble for standing security for the wrong person, and is overwhelmed with joy when they receive the marriage proposal from the Royal Family. The last words of their dying grandfather wasn’t a bluff after all! Prince Shin agrees to marry the all-too-ordinary prearranged bride provided the Chang-Duk Palace be granted independence and the IkWiSa be reduced.
Chae-kyeong, therefore, has no choice but to marry the prince due to her family’s financial crisis. But things aren’t easy, right from the first encounter with the Royal Family. Moreover, seeing that the prince has no affection for her whatsoever, showing careless cynical behavior throughout the wedding process, Chae-kyeong comes to regret accepting the proposal. But it’s too late; the Royal Marriage is the top news in the press, and Chae-kyeong’s house is crowded with reporters. Yool, the son of Prince Hyo-yul who died in an unfortunate car crash 14 years ago, hurries back to Korea under the urgent order of his mother – princess Hye-jung, eager to the win back her husband’s throne. In the airport, he runs into Hyo-rin, who has just returned from her contest but they don’t recognize each other. Yool has been studying fine art in England, and transfers to a high school for arts, where Shin and Chae-kyeong are also students.
At last, Chae-kyeong has made up her mind to join the Royal Family. Lessons for becoming a proper Crown Princess start as she enters the palace. She has to endure hard training, which includes learning proper ways to talk, memorizing the whole wedding process, etc., with the Prince showing no interest nor offering any help to her. Life in the palace is not an easy task from day one. A huge ceremony is held to welcome the new Crown Princess, and with the entire country as witness, Shin and Chae- kyeong are wed in the traditional 21st century Royal procedure.
On the first day after the wedding, Shin and the rest of the adults in the Royal Family go out to fight a little war to ensure they receive what was promised to them for granting the marriage. While Shin is being very serious, Chae-kyeong, on the other hand is busy enjoying the privileges of being the Crown Princess and is slowly adapting to life as a Royal. Chae-kyeong and Shin go to school but Chae-kyeong gets treated like an outcast; the only person that actually talks to her is Yool.
Chae-kyeong, after making her morning calls to the elders of the royal family, is surprised to see Yool inside the palace. Yool, a transfer student in her class, turns out to be prince Ui-seong. At first Chae-kyeong has a hard time adjusting to life in the palace with its strict education and rules, but thanks to the warmth of the emperor and other elders at the palace she starts to find the royal culture attractive. Meanwhile, Hwa-yeong prepares to open a yoga center while plotting with Choi against the other royal family members, while Yool gets closer to Chae-kyeong and her friends.
Thanks to Yool’s help, Chae-kyeong looks good in the eyes of the Queen Mother. In addition, after attending a number of events with Shin, she becomes well known to the public and loved by them for her plain looks and free spirit. Yool tells her she should carry herself with dignity but she ignores his advice. At the opening of the yoga center Hwa-yeong meets Hyo-rin and finds out that she is the Crown Prince’s ex-girlfriend, and when the Empress later finds out the Hwa-yeong has secretly come to Korea and opened a yoga center, she is greatly displeased. Meanwhile, at the palace a party is held to announce the officially married Crowned Prince and his wife to the ambassadors of the constitutional monarchy.
Kam-ae-tta-la starts to feel uneasy as Chae-kyeong adjusts to the palace life. As Hyo-rin thinks back on the good days with Shin she remembers what Hwa-young told her and is determined to get Shin back.Meanwhile, Chae-kyeong misses her family because she hasn’t seen them since she moved into the palace. But soon she and the prince are finally allowed to go visit her family. Chae-kyeong is very happy to be back home but Shin has a hard time adjusting, due to the fact that he has lived his whole life in the palace. Chae-kyeong’s family also feels uncomfortable living in the same house with the him. Chae-kyeong and Shin, who quarrel frequently, end up spending a night together in Chae-kyeong’s small room.
Chae-kyeong and Shin return to the palace and after spending time with Chae-kyeong’s happy and close-knit family. Shin feels sad to see his family who has always been under the control of his strict father, the King. Seeing this, Chae-kyeong comforts him and Shin prepares a car just for her.Persuaded by Hyo-rin, Chae-kyeong and Yool join an equestrian club. Not knowing why Hyo-rin invited Chae-kyeong into the club, Shin’s friends are dissatisfied with the whole idea. Meanwhile, Shin goes to Thailand in place of the Emperor, who couldn’t go because of health reasons.
While Shin is away in Thailand Chae-kyeong gets lonely and gets in trouble for breaking the car. After overhearing some girls at school talk bad about her she gets hurt and asks Yool to just take her away from the palace some place far away from it all. In, Kyeong, Hwan, and Hyo-rin all go to Thailand. Hyo-rin meets up with Shin and asks him to take her to the airport and the two end up spending a day together.
After taking Hyo-rin to the airport Shin makes it to the press conference just in time and gives an outstanding speech. Meanwhile, back at the palace Chae-kyeong gets confined to the palace for leaving the palace walls without permission. Yool after seeing Chae-kyeong get in trouble asks Hwa-young to make him the crowned prince. With the help of Yool, Chae-kyeong successfully finishes the welcoming ceremony for Prince William and Hwa-young starts finding back her and her son’s rights as a royal family by asking the emperor to replace back to them Emperor Hyo-yeol’s powers.
Chae-kyeong insists on riding her horse alone even though the court ladies try everything in their power to dissuade her. While riding her horse she accidentally runs into a stranger in the palace who turns out to be princess Hye-myeong, Shin’s older sister. Shin is happy to see his sister, whom he hasn’t seen for a long time and uncharacteristically shows his softer side to her, telling her his deepest thoughts. The paparazzi photos of Hyo-rin and Shin get reported in the Thai newspapers. The Empress sees the newspaper and gets angry at Shin. Chae-kyeong also finds out about it and gets angry at herself for missing Shin while he was away in Thailand, not knowing that he was with Hyo-rin. Chae-kyeong and Hyo-rin run into each other at school and Chae-kyeong asks her about what really happened in Thailand between the two, but instead of showing a sorry attitude Hyo-rin shows a very dignified attitude causing Chae-kyeong to faint in front of her friends.
Shin tells Chae-kyeong that he is going to withdraw from being Crowned Prince, and she starts to feel frustrated because she does not know his true feelings. Chae-kyeong tries her best to get closer to him but the more she tries the more frustrated and angry she gets through finding traces of Hyo-rin. Eventually she gets into a fight with Shin and breaks into tears. In the palace the plans for the restoration of Prince Yool’s power are in their final stages and Hwa-young and Yool get ready to move back into the palace. The entrance of a new power figure starts to create a division between people of the court over whom they are going to be loyal to, and the Empress and Hwa-young are busy keeping each other in check. The Empress Dowager, who has the final power in deciding whether or not the powers get restored to Hwa-young and Yool, doesn’t know whether giving them the power is the right thing to do or not. Yool and Shin bump into each other in the palace and start a nerve war.
The Empress Dowager, Shin and Chae-kyeong go on a little road trip around Cheju. Shin and Chae-kyeong try everything they can to cheer up the Empress Dowager.The kids at school start looking at Yool through different eyes when they see his new style.Meanwhile, the Empress is busy keeping her eyes on Hwa-young, who has moved into the palace. Hwa-young, scolds the Crown Princess for being lazy and for forgetting about her role and responsibilities as the Crown Princess. After the pictures of Hyo-rin and Shin have been revealed to the public, bad rumors of Shin and Chae-kyeong start to go around. Worried, the adults of the family gather to discuss a plan to stop them before they get any bigger. They decide to have the couple get into the bridal bed.Having no idea of the plan, Shin drinks some medicine that he was told is good for his body and Chae-kyeong gets all dressed up.
After hearing about the couple getting into bed together Yool runs over to see Chae-kyeong. She tells him that nothing happened between her and Shin, and he hugs her, relieved from the unthinkable thought of the two spending the night together. Shin sees this and gets very angry at Yool.Chae-kyeong’s friends get angry at Hyo-rin for starting the rumors and start to criticize her. Chae-kyeong learns a secret about Hyo-rin and starts to feel uncomfortable.Someone leaves a picture inside the Crown Princess’s room. Chae-kyeong is shocked when she sees it and disappears. Shin and Yool soon hear that she has disappeared and instantly go out looking for her.
After finding Chae-kyeong in the Myung-sun Dang, Shin takes her to a place where they can be alone, where they proceed to spill their hearts out and tell their true feelings towards each other. The violence between Yool and Shin becomes known throughout the palace. Hwa-young tells the Empress that she is not going to stand by and watch stuff like this happen ever again, raising the conflict between her and the Empress. The Emperor calls Shin (his son) and harshly scolds him, causing Shin to rebel against him. Despite all the malicious gossip about the Crown Prince and Princess they attend a public conference. When the reporters ask for a loving pose Shin displays his showmanship. Meanwhile, the Empress Dowager senses the tense atmosphere of the palace and suggests that the whole royal family should have a meal together.
Shin and Chae-kyeong leave on a short honeymoon together. Hyo-rin leaves on a trip to where she can find traces of Shin and her love. After getting the cold shoulder from Shin, Hyo-rin remembers what Hwa-young once told her and once again makes a firm determination not to give up. Because of Hyo-rin, Shin and Chae-kyeong feel awkward again and Chae-kyeong starts to feel confused when Yool tells her to leave Shin so he can be with Hyo-rin. The Empress finds out about Hwa-young’s plans and starts to take action… Just then the Crown Prince’s scandal gets known to the public and the palace goes into distress about the matter. The Emperor calls Shin and begins seriously considering whether or not Shin is fit for being Crown Prince.
Chae-kyeong gets angry at Shin for leaving the palace for a while without telling her where he was going. She asks him why he always keeps everything to himself and worries alone. Hearing this he suddenly hugs her and asks her to stay by his side even after he resigns from being Crown Prince. Meanwhile, Hyo-rin, who has come to the palace at the Empress’s request, receives an offer from the Empress to support her. Yool asks the Emperor permission for the Crown Prince and Princess to accompany him on his vacation for his birthday party.
The criticisms of whether the Crown Prince is good enough or not keep rising; even the Emperor starts wondering if Yool is more fit for the spot. Meanwhile, Hyo-rin discusses with Shin her education plans. Yool tells Chae-kyeong, who is feeling miserable at hearing that Hyo-rin and Shin had once promised to go abroad and study together, how he feels about her.
Chae-kyeong gets confused about all the trouble she got into with Shin at Yool’s birthday party. Watching her, Shin feels sorry and apologizes to her but she doesn’t take his apology and instead their anger toward each other deepens. Chae-kyeong hears a rumor about her parents saying that they are profiting with the help of the palace. Hearing this she starts to feel the palace life more and more stuffy and choking. Shin senses her feelings and lets her get away from everything by having her go home for a night. The Empress finds out about it and scolds her for doing whatever she wants to do even though she is the princess. Chae-kyeong gets her feeling hurt and runs out of the palace.
Because of an unexpected incident Chae-kyeong ends up in the middle of a rumor. She meets her greatest crisis after becoming Crown Princess and wanting to figure out a way to stop the rumors on her own she refuses help from Shin and Yool. Shin becomes angry at seeing Chae-kyeong worrying about how to fix her mistakes and orders the Myung Seong Dang to be repaired, but this just causes the Emperor, Hwa-young and Yool to get angrier and more frustrated. After seeing Shin isolate himself from the others of the palace, the Empress calls him to talk as mother and son. She tells him about what she wishes for him. After seeing Hyo-rin working towards of becoming her dream to become a ballerina, he thinks again of his dreams and what he really wants. He finds that his future includes Chae-kyeong and the Empress’s wish and goes to the interview with a firm attitude.
Shin barely manages to cover up for Chae-kyeong’s surprise announcement. The adults of the royal family get very angry at Chae-kyeong’s actions, which were not in line with the ordinary palace rules. Seeing this, Shin feels sad and angry at the same time. Because of the incident, the scandal of the crown princess blows up again and Hwa-young gets nervous so she decides to use Chae-kyeong as the scapegoat to protect her son. Chae-kyeong kneels in front of the Emperor to ask for his forgiveness and cries, and Shin just ignores her. Because of the incident Shin’s ability to be Emperor gets questioned and as this deepens Yool gains trust from the Emperor. In the middle of all this, however, Yool can’t stand looking at Chae-kyeong having such a hard time and reveals his feelings in front of all the royal adults.
Yool tries his best to keep faithful to his heart even if it means breaking the rules. Shin insists that rules and regulations are the strength that holds the palace together. Even though their ways of following them and carrying them out are different, the person they want to protect are the same. Chae-kyeong also feels bad watching the people she loves and cares for getting hurt, while the reasons and reality also grow farther and farther apart. Meanwhile, the Emperor worries about the behavior of Yool and the other royal family members.
Shin gets driven into a corner as an arson suspect. He insists that he is innocent but all the evidence leads back to him. Only Chae-kyeong believes him to be innocent and feels bad looking at his drooping shoulders. Shin, knowing that someone actually cares and loves him, doesn’t feel lonely anymore and calmly handles the situation. Yool senses that it was all part of his mother’s plan and tells her to stop whatever she’s planning on doing but she does not know how to stop or even control her ambitions. As more incidents happen the existence of the palace starts to get questioned by the people and in order to stop all the rumors the Emperor suggests that the crown princess should practice more self-discipline.
As the investigation of the arson incident furthers and the facts about it get revealed Shin gets more and more accused of being the cause of it. In the midst of all this Chae-kyeong and Shin’s feelings towards each other grow even stronger and they fight together to get through this storm. The two already resemble each other regardless of Chae-kyeong having told him that she has studied hard to be fit for him. The Emperor once said that “Apart from the truth of the incident, the person worthy of the imperial throne is the one who receives the love and honor of the people.” Hwa-young smiles a smile of satisfaction and throws in her last card. The Empress sees that Chae-kyeong has slowly started to show the qualities of a crown princess and for the first time they actually sit down and talk with each other. The Empress encourages her and gives her strength.