College girl and the guy next door! Cousin and the woman next door! Min-joo likes her cousin Min-cheol, but Min-cheol rejects her. Min-joo, whose self-esteem has fallen, seduces Yeong-seok, the guy next door, to regain his self-esteem. Yeong-seok's wife, Soo-jin, is having an affair with Min-cheol.  The four secret private lives are exposed by chance, and Yeong-seok and Soo-jin use Min-joo and Min-cheol's minds to continue their affair.