Scooby-Doo and the Witch's Ghost

Scooby-Doo and the gang of Mystery, Inc. join a famous horror writer to celebrate Autumn Harvest in Oakhaven, Massachussetts. But after pulling the cover off a fake witch's ghost during a Hex Girls concert, they soon discover that there may be a real evil witch. Did the writer trick them into helping uncover an evil spell book for his own demonic use? It's up to Scooby, Shaggy, Daphne, Fred and Velma to save the world.