Seo Hyun is an ordinary housewife in her late thirties with a ten-year-old son and a successful architect husband. For Seo Hyun, life is a series of banal routines, but she is well provided with upper-class comforts. Her sheltered life is suddenly threatened with the appearance of Woo In, her much younger sister's attractive new fiance. Woo In approaches Seo Hyun and attraction evolves into a passionate affair. Seo Hyun is aware that falling for the younger man will destroy her and her family, but she cannot help herself and the new feelings that are stirring within.