Chun Ji Ae and Yang Bong Soon are high school classmates who did not have the best relationship with each other. Ji Ae was the most popular girl in school whereas Bong Soon was the girl that was always made fun of. Years later, their roles are reversed as Bong Soon's husband, Kang Joon Hyuk, is very successful whereas Ji Ae's husband, Ohn Dal Soo, is just an average company worker. Things get complicated when Dal Soo starts an extra-marital affair with his boss's wife, Eun So Hyuk. How will Ji Ae react to this?