The Korean movie 18+ The Second Mother tell about a beautiful girl who used to work as a waitress at a karaoke bar named Hee-ran (Yoon Seol-hee), who met a successful middle-aged man named Se-min (Lee Yo-seong) through a marriage consulting company. Her irresistible beauty to a single father like Se-min made him quickly want a marriage contract, and of course in return he would pay Hee-ran every month to become his wife and of course she would also be the stepmother of his son, Se-gyu.
Hee-ran once thought that this was a very good job, but in reality it was not like what she thought, this marriage was boring. Se-min only needs her at night while Se-gyu (Kim Hong-je) doesn’t seem to consider her as a stepmother, the teenage boy looks at her like he wants to “eat her alive” and often relieves his desires. Things get complicated when while Se-gyu starts to have feelings for Hee-ran, the girl later falls in love with Tae-yeong (Kim Min-seong-II), a friend of Se-min when he visits the house,…