Childhood sweethearts Cha Song-Joo and Han Jung-Suh’s love is tested when Jung-Suh’s father remarries, bringing a new stepmother and introverted stepbrother, Han Tae-Hwa, into the picture. As Tae-Hwa falls for Jung-Suh, her scheming stepsister, Han Yu-Ri, sets her sights on Song-Joo. Despite the growing tensions, nothing seems to break the bond between Jung-Suh and Song-Joo––until one fateful night, when Jung-Suh is hit by a car and believed to be dead. Losing her memory in the crash, Jung-Suh is taken in by Tae-Hwa, who relocates her and gives her a new identity. Five years later, as Song-Joo is about to marry Yu-Ri, he spots a woman who looks exactly like Jung-Suh, sparking a quest to uncover the truth.