The film takes place over the course of Halloween in the fictional town of Warren Valley, Ohio. Its story is told in a nonlinear narrative, with characters crossing paths with each other throughout the film. At the centre of the story is Sam, a peculiar trick-or-treater dressed in pyjamas and a burlap sack, and appears to enforce the “rules” of Halloween.
In the opening scene, Emma and husband Henry return home after a disastrous night. Emma tears down the seasonal decorations before the night’s end, and is murdered by an unseen assailant. Henry later discovers her mutilated corpse on display.