On the way to finding a surrogate wife, Shin runs into a 17-year-old girl, Ok-nyo (Kang Soo-yeon).

The stubborn nature of Ok-nyo attracts Shin and influences him to choose her to become the mother of his child.

Ok-nyo has to obey rules which keep her hidden during the day and delegates her to perform the mating ritual during Shins wife's hours of choosing.

With Shin's infatuation and Ok-nyo's attachment, both secretly meet for passionate affairs.

Ok-nyo's mother tries to dissuade her, and to break off the relationship, by telling her the realities of life.