The villain Scarecrow's servants, the Scaredy Crows, are coating Gotham City with fear dust, and it is up to Ace the Bat-Hound to find a way to save Halloween for the city's children.
When Swamp Thing is called away to help with a fire elsewhere, Solomon Grundy and his zombie pets decide to take over the swamp--and it is up to Ace the Bat-Hound and the Swamp-Pets to repel the invasion.