Nam Yoomin, a full time department store worker, begins to feel skeptical about her own life. She decides to quit her job due to a conflict with her manager. However, when she enters the manager's office. She comes face to face with the manager who has now turned into a monster. Yoo Min immediately runs away from the manager, but encounters another monster and faces danger once again. Outside the department store, a world experiencing doom had already begun unfolding.