The Heirs

17-year-old Cha Eun-Sang takes her ne'er-do-well sister's wedding in the U.S. as a chance to escape her life as the daughter of a mute housemaid. There, she runs into mysterious Kim Tan, the young heir of a wealthy family.

Stranded by her sister and with her passport taken away by the police, Eun-Sang accepts Kim Tan's offer of staying at his house. Unfortunately, it puts her right in Rachel's line of fire, who's not happy to see another woman in Tan's home.

As Tan and Eun-Sang get to know each other better, Tan finds himself growing more attached to her. Meanwhile, Eun Sang's mother accidentally overhears her employer's mistress talking about getting rid of his second wife.

Rachel returns to Korea, and so does Eun-Sang who finds that her mother has moved into the Kim household. Missing his family and Eun-Sang, Tan decides to return to Korea as well, much to Won's dismay.

Tan causes an uproar in his house and with his social circle upon his surprising return to Korea. Tan's father, who has kept tabs on him and Eun-Sang, offers her a scholarship to Jeguk High School, a school for the elite and wealthy.

Eun-Sang and Tan begin their first day at Jeguk High School. While Eun-Sang is introduced to the social class system of the school by Chan-Young, Tan and his former best friend, Young-Do, look at each other fiercely in an empty classroom.

Young-Do becomes suspicious of Eun-Sang's social status and her relationship with Tan when bullying a boy of a lower social class. Rachel suddenly visits Young-Do when her mother asks her to take a family photo.

Rachel overhears Tan confess his feelings to Eu- Sang, who is reluctant to reciprocate due to their class differences. Meanwhile, Young-Do disrupts his family's photo shoot by inviting one of the women his father is having a dalliance with.

Surprised by Kim Tan's kiss, Eun-Sang runs away. Later, Tan and Young-Do fight once more. Meanwhile, Ki Ae pretends to be Eun-Sang's mother at a parent's meeting, leading to the whole school start digging up on Eun-Sang's background.

The midterm exam results are released as the students prepare for school camp, but Tan decides not to join the class after having a falling out with Eun-Sang. Rachel requests Ji-Sook and Esther for an end to her engagement with Tan.

The love triangle between Tan, Eun-Sang and Young-Do heats up. As the students return to school, the engagement between Rachel's mother and Young-Do's father goes public. Jin-Sook tells Won that Tan is soon to become a majority shareholder.

Young-Do discovers Eun-Sang's secret about her mother working as a maid for Tan's family. Tan reveals his own secret to Rachel. Meanwhile, Won is warned by his father to not pursue a relationship with Hyun-Joo.

Rachel visits Young-Do and asks why Tan hid the fact that he was an out-of-wedlock child. Eun-Sang and Tan announce their relationship, but it leads to a whole mess of problems for everyone around them.

Tan and Young Do are forced to confront their past as they are caught up in a fight yet again. Rachel takes over as the new bully in town and orders catering where Eun-Sang works, planning to expose her at Chan-Young and Bo-Na's party.

Eun-Sang deals with the aftermath of telling everyone the truth about her family. Meanwhile, Ki-Ae manages to call off Rachel and Tan's engagement but it leads to Kim Nam-Yoon to take matters into his own hands.

Tan hears from Jae-Ho that Chairman Kim is sending Eun-Sang to study abroad. Meanwhile, Young-Do is upset by everyone's treatment of Eun-Sang and Won fights for his rightful position in Jeguk Group.

Everyone is surprised by Eun-Sang's sudden disappearance except for Tan's father. Tan and Young-Do go to extreme lengths to find Eun-Sang, but soon Tan realizes that the only way to protect her is to leave her.

Chairman Kim and Ki-Ae argue, resulting in her decision to separate. Moved by his brother's pain, Won steps in to help Tan and Eun-Sang regain their footing. Young-Do makes a painful choice for himself and his friends.

Tan makes a public stand against his father for Eun-Sang's sake, but his real obstacle is getting her mother's approval. Young-Do finds his mother as the authorities prepare to prosecute against his father for improper business practices.

The fate of Jeguk Group lies in Tan's hands as he asks Young-Do for help and meets with foreign shareholders to receive a power of attorney and take charge of the company. Young-Do reunites with his mother as his father is arrested.