Grandmother Aggie sweeps Marnie and Sophie off to Halloweentown to investigate a series of strange occurrences that seem to have stripped the community of its magic. But why? It isn't long before they discover that an angry warlock has taken Aggie's spell book with evil intentions—to turn every human into whatever costume they are wearing at midnight on Halloween.
Grandmother Aggie (Debbie Reynolds) sweeps granddaughters Marnie and Sophie off to Halloweentown to investigate a series of strange occurrences. When they arrive, the vibrant community seems to have lost its magic, and its once-colorful citizens have become gray—literally—and boring. But why? It isn't long before Aggie discovers that her spell book has been stolen, and the trio sets out to find it. They discover that an angry warlock plans to permanently turn every human into whatever costume they are wearing at midnight on Halloween and has taken the book so Aggie can't use it to reverse his spell. It's a race against time, as Marnie must use her skills to defeat the young warlock threatening to change Halloweentown for eternity.