Heechul is a hard-working guy who finished his university studies and went to work from Gangwondo to Seoul to live a better life and to help his family, He meets his boss's girlfriend ,Yoona.whom fall hard for him despite her boyfriend loving her, Heechul doesn't know what to do ,to keep loving her or to stay away from her because of his guilty feelings toward the person who helpt him the most his boss,Choi Siwon.