Professor Jo Young-hwa's family is a model family consisting of his wife, son, college senior Yun-gu, and daughter Hye-young. They are introduced to Daeyoung Industry's president Kim and his wife. Yun-gu and Hye-young see their father getting in a taxi with Man-ja, a woman in her 20's. Man-ja's single pad becomes a place for them to share their "romance gray" and Bo-young becomes a slave to Kim's money. Prof. Jo learns to dance from Yun-gu to keep up with Man-ja. One day, in Bo-young's apartment, Kim, Prof. Jo, Man-ja and Bo-young converge and the "romance gray" of middle-aged men becomes a hot issue.
