Halloweentown II: Kalabar's Revenge

A young witch and her grandmother work together to foil the plans of a wicked warlock's son before he can use powerful spells to create chaos in the world.
The Cromwell clan lives in the real world, except for their grandmother who lives in Halloweentown, a place where monsters go to escape reality. But now the son of the Cromwells' old enemy Kalabar has a plan to use the grandmother's book to turn Halloweentown into a grey dreary version of the real world while transforming the denizens of the real world into monsters.