Shaggy and Scooby decide to throw a housewarming party, but their neighbor and president of the Housing Association, Thurston Havansimp, sets out on derailing their plans. He threatens to cite them with enough code and permit violations to evict them from their house and the neighborhood. Meanwhile, Dr. Phibes finds about the party and sends a deadly robot to the Shaggleford Mansion with orders to annihilate the dynamic duo.