The relationship of childhood sweethearts Cha Songjoo and Han Jeongseo becomes complicated when Jeongseo's father remarries. Along with a new stepmother, Jeongseo also has a new introverted stepbrother, Han Taehwa and a scheming stepsister, Han Yuri. Gradually, Taehwa falls in love with kind-hearted Jeongseo and Yuri decides to pursue Songjoo. Nothing can shake the bond between Jeongseo and Songjoo, however, not even Songjoo's departure to study abroad in America. On the night of his return, however, Jeongseo is mysteriously hit by a car and believed dead. Having lost her memory in the crash, she is taken in by Taehwa, who relocates and gives her another name. Five years later, on the eve of his engagement to Yuri, Songjoo sees someone who looks exactly like his lost love Jeongseo.