A long long time ago a wizard was put to death, but he swore vengeance on the townsfolk that did him in, particularly Arthur Kelly's family. Arthur had done the final graces on him when he came back to life as Mr. Jack the Pumpkin Man. The Kellys proliferated through the years, and when some devil-may-care teens accidentally unleash Jack-O, young Sean Kelly must stop him somehow as his suburban world is accosted and the attrition rate climbs

Triton Indutries has created a genetically-engineered creature using DNA from human sources. During the course of the experiment, however, the host mother carrying the mutant escapes from the laboratory compound, giving birth shortly thereafter. The intellient "baby" beings hunting down and killing its male DNA donors, while at the same time trying to mate with its female donors. The head of the lab wants to destroy the monster before the press can get wind of the story, but the former head of security wants to expose the whole thing.