(Many thanks to fellow addict bigfatcat from Indonesia for graciously sharing this summary and ending of Bad Girls with us. KoreanWiz welcomes others to share info about this and other dramas.)
Summary of Bad Girls: (there is a warning below before the ending is disclosed)
Jae-kyung (Park Sol Mi), Yeol-mae (Sung Yuri) and Yeon-hee (Kim Hye Ri) are three best friends. They are not just normal best friends, they are inseparable. Yeon-hee is married to Jun Taek-su, Jae-kyung is going out with In-ku, and Yeol-mae's boyfriend is Bong-chul.
In the beginning, all three men define "bad girls" as girls that are sexy, smart and good-looking. This is the type of girl that guys should be scared of.
Taek-su is having an affair with a female fellow worker in the office and was caughte by In-ku. During competitive week to gain a position raise, one of the higher managers tries to sexually harass Jae-kyung since he thinks that she is the kind of woman that is willing to do anything to get a raise. However, she manages to escape from the tragedy and injures the manager. In-ku finds out about this and keeps quiet about it even though he is hurt by it. In-ku manages to get the position he wants based on Taek-su's recommendation. In return for the recommendation, In-ku agrees not to disclose about Taek-su's affair to Yeon-hee. However, in the end the Yeon-hee finds out about it on her own.
Jae-kyung is sent to work as a manger in one of the company's supermarket branches that is about to be closed down. There she meets Sin-ho, who falls in love with her. Bong-chul is a bum that can't get a job and sits around at home while Yeol-mae, who loves him deeply, works to support him. She gets him a job in the company's main branch where Taek-su works. Bong-chul then falls in love with the woman that Taek-su is having an affair with.
Given the raw end of the relationship with their men, the three girls seek revenge. This is where the drama gets interesting. The revenge is unique and shows how these three women prove themselves not be underestimated by men.
Ending of Bad Girls: (do not proceed if you don't want to know the ending of this drama.)
The best way to get their men back is by taking the things that they love the most away from them. ForTaek-su, this means taking his women, money, job and family away from him. Yeon-hee uses Bong-chul to separate Taek-su from the woman Taek-su is having an affair with (who Bong-chul also is in love with). As soon as Taek-su breaks up with that "other woman," Yeon-hee then makes sure that the affair is known to the company. Taek-su and the other woman end up getting fired by the company.
Yeol-mae and a friend of Yeol-mae create a fairy tale story that Yeol-mae is the daughter of a rich designer. Yeol-mae then suddenly changes to a wealthy princess. Upon learning of Yeol-mae's wealth, greedy Bong-chul wants to marry Yeol-mae for her money. He does everrything to get Yeol-mae's (pretend) mother's approval by showering them with lavish gifts. In the end, he is in a lot of debt with the loan shark and the bank. On top of that, on their engagement day, Yeol-mae suddenly breaks off her engagement to Bong-chul.
For Jae-kyung, most of the workers do not like her at the supermarket branch she is transferred to. They see her as the mean manager that doesn't treat others as human beings. Her assisstant, Kim Sin-ho, dislikes her in the beginning but in the end, falls in love with her. Jae-kyung, however, loves In-ku deeply. Even though In-ku loves her back too, he puts his career first in front of her. His main aim is to challenge the main director of the company, which is his late father's closest friend. However, he overdoes everything and ends up breaking the law. Jae-kyung wants him to give up his revenge and live normally like they did before, but In-ku doesn't want to listen to her and goes through with his original plan (for revenge). In the end, Jae-kyung reports him to the police and he is arrested for the crimes he did in the company.
In the end, Yeon-hee divorces her husband and lives happily with her daughter. Yeol-mae goes back to study. Jae-kyung goes to study abroad for one year with Sin-ho waiting for her return.