A 34-year-old woman named Lee So-young looks 10 years younger than her real age and manages to fool almost everyone around her. With a large family debt to take care of, only a high school degree, and big dreams of becoming a fashion designer, So-young has her work cut out for her. The only thing she has going for her in the cutthroat fashion world is her youthful appearance. In a fortunate accident, she gets mistaken for her younger sister, Lee So-Jin, for a modeling job and manages to land a position at her dream fashion company. There, she meets one of the managing directors, Choi Jin-wook, who looks far older than he really is. The two of them clash, especially since Jin-wook treats So-young with disrespect.