Da Eun, who was abondoned by her father at 6 years old, looses her memory after a car "accident". Jonghyun, whos family took care of Da Eun as their own daughter, attempts to make her regain her memory back. Through the story, you see how Jonghyun slowly started falling for his "sister" and how she eventually falls for him, too. She's indecisive on whether to find her biological father who had forsaken her or to continue life with that doubt...