Kim Hyun Ju , who starred as Yun-hee, and Kim Ji Ho , who starred as Tae-hee, born into a one-parent family after their mother died giving birth to Yun-hee. Their father, who loves his daughters dearly, vowed not to marry again and struggled to raise them. Unfortunately, their father, already suffering from leukemia, was killed in a car-accident. The girls were left to fend for themselves but a series of events created by a bunch of gangsters separated the sisters for fifteen years, with Yun-hee growing up as Sun-Woo and being abused by a family (Seung-hee especially) forced to adopt her because she was knocked down by their truck while Tae-hee, who spent fifteen years with her grandfather, becoming a successful entrepreneur. Chul-woong would frequently stand up for Sun-woo, and once ransacked their house when Sun-woo was being abused. Seung-hee later pretended to be Yun-hee in place of Sun-woo upon receiving a letter from Tae-hee who was searching for her sister. Sun-woo took refuge at Chul-woong's house at this point in time.
An internal strife develops when Jae-hyuk decided to carry out his business vengeance plans against Tae-hee's grandfather, who had indirectly caused his grandfather's death as a child. Shortly before the sisters reunited, their grandfather was killed in a car accident and after they reunited Chul-woong was killed by gangsters who gave him several stab wounds when Yun-hee was kidnapped by gangsters on their wedding day.
In the beginning of the drama, both sisters, Tae-hee and Yun-hee harbored feelings for Jae-hyuk. Jae-hyuk and Chul-woong both have feelings feelings for Yun-hee, but Jae-hyuk is engaged to Tae-hee. Seung-hee has feelings for Chul-woong, which makes her jealous of Yun-hee. She becomes even more jealous and spiteful of Yun-hee upon realizing that Yun-hee was the sister whom Tae-hee was searching for, as she grew up in a, what she believed, a poor home. Yun-hee marries to Chul-woong in the end, realizing how great his affections for her were, that he died protecting her.