Little Hannah Marie is excited to be going trick-or-treating with the older kids. But when her mean cousin Jimmy tries to ditch her in the dark basement of a spooky house, Hannah is rescued by her Scary Godmother and whisked away to the best Halloween party ever! It's a 'who's-boo' of monsters with Skully Pettibone, Harry The Werewolf, Orson, Bug-A-Boo and more, all in one unforgettable night of big screams, strange pizza and the ultimate plan for revenge on Jimmy and his friends.