With fake monsters and candy galore, Halloween is heaven for these hungry foodies going door-to-door. But this year, their sweet holiday turns sour when the neighborhood pumpkin patch is infected by toxic ooze, creating high-flying jack-o-lanterns, and a king-sized pumpkin leader squashing everything in its path. It’s up to Scooby-Doo and the gang as they team up with their pals, Bill Nye the Science Guy and Elvira, Mistress of the Dark, to solve this mystery of gigantic proportions and save Crystal Cove!