It is almost Halloween in the sleepy New England town of Blackwood Falls. Leaves litter lawns and sidewalks, paper skeletons hang in the windows, and carved pumpkins leer from front porches. The Doctor and Martha soon discover that something long-dormant has awoken, and this will be no ordinary Halloween. What is the secret of the ancient tree and the book discovered tangled in its roots? What rises from the churchyard at night, sealing the lips of the only witness? Why are the harmless trappings of Halloween suddenly taking on a creepy new life of their own?