Lee Seo-yeon, a free-spirited woman, is having a secret affair with Park Ji-hyung, an architect who has a fiancée. Upon hearing that Ji-hyung's parents set the date for his wedding, Seo-yeon splits up with him. But she has no time to lament over her painful breakup, as she gets diagnosed with early on-set Alzheimer's, a very unlikely disease for a 30-year-old woman. Ji-hyung happens to learn the shocking fact, and he breaks off his engagement only two days before the wedding to return to his ex-girlfriend. Despite vehement opposition from his parents and even from Seo-yeon herself, he never gives up on her and marries her without delay. The doting husband is devoted to taking care of his ailing wife, who is losing her ability to remember. Despite her distressing condition, the couple tries to hang on to love and experience it to the end. They have a baby girl and find happiness in their married life from time to time, even though both are well aware that a tragic end awaits them.