Cinderella and the Four Knights

Ha Won is thrilled when she is accepted into college but an unforeseen circumstance causes her to give up the tuition money she had worked so hard to save. But as if by fate, Haneul Group's first-in-line heir, Hyun Min appears before her with a lucrative part-time job offer. However it leads her to an unexpected place where she is put in a difficult situation and confronted by temperamental Ji Woon, the second oldest of Haneul Group's potential heirs.

As the news spreads of Ha Won and Hyun Min's engagement, she transforms from a regular part-timer to the Nation's Jackpot Girl. And after Chairman Kang witnessed how she handled Hyun Min and Ji Woon at the wedding, he comes to her with a unusual job offer : to make his three grandsons into decent human beings.

Ha Won begins living at Haneul House with the three cousins who can barely stand each other's presence. Ji Woon is always mean to her, while Hyun Min wants to keep their engagement facade alive, it's only due to the kindness of Seo Woo that Ha Won can be at some ease. But then she gets her first mission from Chairman Kang, which soon becomes more like "Mission Impossible."

For her first mission, Ha Won is tasked to get the three cousins to eat their first meal together. She resorts to betting and trying to entice them with their favorite foods but they don't seem to budge...and then comes Ji Woon's bombshell! - That he's going to try to steal Ha Won away from Hyun Min.

Ha Won continues to have confused feelings towards Ji Woon when she gets her second mission. Through this mission she learns of more of Ji Woon, Hyun Min and Seo Woo's past and the pain that lies there. She sincerely tries to get the three of them to open up but as the mission's deadline arrives, will she be able to succeed?

Ha Won waits for the three cousins at the final destination of Mission Two. With no word from any of the cousins, will Ha Won be able to complete this mission successfully? Also, Ha Won's graduation day arrives and because of a rumor started by her stepsister Yoo Na, Ha Won is put in a sticky situation. Who is the person that arrives at that moment to save Ha Won?

After Hyun Min confesses that he wants to start a real relationship with her, Ha Won still finds herself at the brink of tears, but for what reason? Ha Won finds herself back at Haneul House and Chairman Kang comes to her with her next mission! Go on a trip with all three cousins! Will Ha Won successfully be able to convince them all?

In the aftermath of Ji Woon's and Ha Won's kiss, an accident involving Ha Won cuts the trip short. The fact that Ji Woon does not seem to care that she got injured hurts Ha Won's feelings. But a romantic moment occurs between the two of them. When Hyun Min hurts Hye Ji again, it causes her to turn to Ji Woon and ask him to accept her.

Hye Ji's sudden confession to Ji Woon has both Ha Won and Hyun Min spinning. Seo Woo resolves to show Ha Won the song he wrote for her, while Ha Won and Ji Woon enjoy a nice drive. But a sudden call causes Ji Woon to leave Ha Won and rush off elsewhere.

Hye Ji staying at Haneul House gets Ha Won worried. She wants to show the Kang cousins a good side of her that is different from Hye Ji but an unpredictable response becomes apparent. Hye Ji realizes that Ha Won likes Ji Woon, causing her to lie to Ha Won that she and Ji Woon are dating. Ha Won is disappointed after she realizes that she was wrong when she thought that Ji Woon liked her.

Ha Won is shocked when her so-called biological father appears and Ji Woon comes to her to comfort her. But knowing about his relationship with Hye Ji causes Ha Won to suppress her feelings. Hye Ji decides to resolve her feelings for Ji Woon and Hyun Min but the more Hye Ji tries to pull away from Hyun Min, the more determined he becomes to get involved in her life.

Ji Woon ♡ Ha Won. The beginning of a secret relationship! But a clause in Ha Won's work contract that forbids dating within Haneul House suddenly causes this newly blossomed relationship to encounter a hurdle. And as Hye Ji and Hyun Min's relationship continues to get tangled, the reason why Hyun Min has been pushing Hye Ji away all these years comes to light.

Haneul House encounters a crisis when Chairman Kang suddenly collapses. Ha Won thinks that the Chairman collapsed because of her so she prepares to leave Haneul House. Ji Woon finds notes that his mother left behind and becomes angry at his grandfather for being the cause of his parents' separation. Ha Won finds Ji Woon and brings him proof of his grandfather's feelings towards him and tries to persuade him to go to his grandfather before it is too late.

Ji Woon decides to go through with the surgery for his grandfather even though he is warned that due to a complication, he may never wake up. He asks the doctor to keep this fact a secret. Ha Won fulfills Ji Woon's wish that she stay by his side but she decides she will leave him once his surgery is successfully over. But in the operation room, someone's heart stops.

Ji Woon is in a coma after going into shock during his surgery. Ha Won stays by his side, revealing the true extent of her feelings towards him but he still does not awaken. Chairman Kang recovers and Ha Won asks to be allowed to stay by Ji Woon's side until he wakes up. But not wanting to see Ji Woon hurt further, Chairman Kang coldly asks Ha Won if she can really choose Ji Woon over money.