One day, Eom Jeon-woo wakes up trapped in an unfamiliar station with no exit. There, he meets another survivor, Seo Myeon, and together they search for a way out—only to be ambushed by monstrous creatures. At the brink of death, they are rescued by Sang-jun, a fellow survivor, and continue their perilous journey. However, during their escape, Eom Jeon-woo sustains critical injuries from the monsters and begins gradually transforming into one of them. Will they survive and escape the station alive?