Origin of Monogamy(결혼의 기원)

Kim Seon-ae works at the AIDS Research Laboratory, Jang Mi-joo works at a nooky establishment and Han Seong-ae is a psychiatrist. Seong-ae talks to single men about sex and is responsible for her friend Seon-ae's hypnotic treatment. One day, Seong-ae hears something shocking about AIDS during therapy... Seon-ae shudders at the mention of men and doesn't want anything to do with them. Seong-ae tries to treat this woman hooks her up with Jae-san at a club. Mi-joo is pressured to perform oral sex in order to marry Jae-seon as she is bad-off and survives every day by working at the sexual establishment. Mi-joo had lied about her family being well-off and when Jae-san asked to visit her home, she became surprised. She calls Seon-ae who she doesn't usually call and asks her for a favor. Seon-ae meets a man for the first time at a club!!! Mi-joo can't refuse anything her boyfriend asks for! Same goes for Park Jae-san. The three of them are out for trouble...