No one is born evil; only good people turn bad. A mysterious empty package that appeared out of nowhere completely changed the life of deliveryman Ji Wen. As the Special Cases Unit stepped in to investigate, a series of bizarre and inexplicable incidents followed one after another: the recipient-who had been dead for a week-personally signed for the package; a young woman in the dead of night pleaded for help in finding the murderer who killed her; and a corpse that had already been buried knocked on a door late at night and killed someone. Do inexplicable supernatural phenomena truly exist in this world? And what is truly more terrifying: demons, or the human heart?