The fat orange cat Garfield persuades the dim-witted dog Odie to accompany him when he goes trick-or-treating on Halloween night, merely so that there will be two sacks of candy instead of one, meaning that there will be twice as much candy for Garfield. Following a disastrous attempt to reach more houses on the other side of the river, and gain more candy from the people that live in them, the two animals eventually find themselves at a run-down old house. The old man who lives there warns them that they could be in great danger. Exactly one hundred years earlier, a band of pirates buried their treasure beneath the house. At precisely midnight, their ghosts will be coming to retrieve it.