In the brilliant legacy, Go Eun-seong (Han Hyo-joo) is a simple and beautiful girl who lived with her father and younger brother after her mother passed away due to illness when she was six. When she was in high school, her father remarried, giving Eun-seong a half-sister named Seung-mi (Moon Chae-won). Her stepmother, Baek Seong-hee (Kim Mi-sook), is a very calculating woman who outwardly shows great care and affection towards Eun-seong and her brother, but behind the scenes has designs on Eun-seong's father's wealth.