Han Dongwoo and Choi Yuna grew up together like brother and sister since childhood.
Their first love, which began in high school, eventually led to marriage after college and employment.

But after getting married, Dongwoo learns a shocking truth.
Yuna, who was pure and affectionate during the day, became an unbelievably sensual and provocative woman once night fell.

Every night, she seduces him with a different side of herself.
As Dongwoo falls deeper and deeper for her, he slowly begins to uncover the true face his wife had been hiding.