A hot-shot architect returns home from his latest business trip with a surprise: an ornate old clock rescued out of a soon-to-be-demolished mansion in Amityville, New York, that brings about a seemingly unstoppable demonic force.

Four bloodthirsty demons stow away on a truck belonging to the owners of a carnival attraction and, after arriving at the fairgrounds, hole up inside the ride, which becomes a sensation after patrons believe the creatures are part of the show.