Grandmother Aggie (Debbie Reynolds) sweeps Marnie (Kimberly J. Brown) and Sophie (Emily Roeske) off to Halloweentown to investigate a series of strange occurrences. When they arrive, the vibrant community seems to have lost its magic. It isn't long before Aggie discovers that her spell book is stolen and the trio must find it. They discover that an angry warlock has taken the book and plans to permanently turn every human into whatever costume they are wearing on Halloween.