Ranger Brody, with the help of his nephew and niece, is preparing to open the brand-new campground for the season. Everything is in order and the camp seems peaceful until a giant rat, mutated from multiple dumping of toxic wastes, begins killing the campers and rangers.

In Port City, North Carolina, a vagrant discovers plans for an invasion. His attempts to warn law enforcement are ignored but when the Sheriff notices odd interactions with other townsfolk, he begins to look into the claim of a sleeper cell living amongst the locals.