Jung Suh (Park Shin Hye / Choi Ji Woo) and Song Joo (Baek Sung Hyun / Kwon Sang Woo) grew up together. They were always there for each other. Tragedy begins when Song Joo begins his studies overseas without Jung Suh. Jung Suh's father remarries Tae Mira. Mira takes in her two children from a previous marriage, Tae Hwa (Shin Hyun Joon) and Yuri (Kim Tae Hee). Yuri is envious of the life that Jung Suh leads and is determined to take everything away from her, including Song Joo.
Tae Hwa begins to develop feelings for his stepsister, however, Jung Suh still loves Song Joo. Five years later, tragedy occurs when Jung Suh gets into a car accident causing her to lose her memory. Together with Tae Hwa, they start anew. Song Joo is led to believe that she is dead. However, when they meet again one day, he is determined to remind her of the love they had for one another. When fate finally seemed to be on their side, Jung Suh is diagnosed with eye cancer.