Citizens from upscale Gangnam in Seoul start experiencing unusual and terrifying symptoms, devolving into inhuman creatures, leaving only a few survivors with the possibility to make it out alive.

A-Ra (Ha Na-Kyung) works at a real estate office as the director. She also has clandestine meetings with some of her male customers for fun. Meanwhile, Mi-Yeon (Kwak Hyun-Hwa) begins working at the same real estate office. She hates it when men look at her body. One day, Mi-Yeon notices that somebody is secretly watching her and she gets excited. Mi-Yeon then begins exposing herself to the person watching her …

Yoona has managed to mature into a fine woman despite her rough childhood. One day, when Yoona finds out that her mother has become ill, she travels home for the first time in a long while. However, this trip doesn’t become what Yoona was expecting it to be…