Soo-Jin (Song Ji-Hyo) is a producer at a film production company. Her company decides to make a film based on a popular webcomic by Myeong-Soo’s (Byun Yo-Han). The webcomic is about Myeong-Soo\'s ex-girlfriends. It just so happens, Soo-Jin is also an ex-girlfriend of Myeong-Soo. Now, Soo-Jin has to interact with her ex-boyfriend and his 3 ex-girlfriends: Hwa-Young (Lee Yoon-Ji), Ji-A (Jang Ji-Eun) and Ra-Ra (Hwa Young).
\'Ex-Girlfriends\' Club\' talks about contrasting mindsets of men and women when they get into a new relationship. A man becomes curious about his current girlfriend’s ex-boyfriends and a woman wonders about her ex-boyfriend’s current girlfriend.