"The Heirs" depicts the friendships, rivalries and love lives of young, rich heirs led by Kim Tan (Lee Min-Ho) and a girl named Cha Eun-Sang (Park Shin-Hye). Unlike the others, Cha Eun-Sang is considered ordinary and comes from a poor background.
18-year-old Cha Eun-Sang lives with her mother who is mute. Her mother works as a housekeeper and Eun-Sang also works part-time jobs to help out. One day, Eun-Sang's older sister (Yoon Jin-Seo) calls from the U.S. and informs them that she will marry. Eun-Sang's mother then asks Eun-Sang to send her older sister some money from her savings account. Eun-Sang isn't happy with her situation and decides to go to the U.S. herself to see if she can start a better life with her sister.
When Eun-Sang arrives in California she is in for a shock. Her older sister lives in a filthy home with a deadbeat boyfriend who seems violent. Her sister is also not getting married or going to school and works full-time as a waitress. When Eun-Sang finally tracks down her sister working at a beach front restaurant, she takes the money Eun-Sang brought for her wedding and leaves without even saying goodbye. Eun-Sang's dreams of starting a better life in America quickly vanishes and she crumbles to the ground in tears.