Before the events of 'Welcome to Dead House', there was a manufacturing accident at an industrial facility on the outskirts of town, just over the bridge from the 'Welcome to Dark Falls' town sign. In the book the accident occurred at the plastics factory many years ago. In the TV adaptation, we see an old newspaper article which details that the accident occurred three years ago at the 'Dark Falls Chemicals' plant, contaminating all the workers, who then became the undead. They feed on the fresh blood of the living once a year, who also become undead as well, and part of the Dark Falls secret.