One day, when Jin-Woo Lim opens his eyes, he finds himself trapped in a station he has never seen before with no exit. There, he meets another survivor, Seo-Yeon, and while searching for the exit together, he is attacked by monsters. At a critical moment, he is saved by another survivor, Sang-Jun, and they travel together, but while searching for the exit, he is seriously injured by a monster and gradually transforms into a monster. Will they be able to escape the station alive?(Source: Naver, translated)