Goosebumps 14 -The Werewolf of Fever Swamp

Grady Tucker and his sixteen year-old sister Emily have both moved to a new house with their scientist parents who are attempting to determine whether deer can survive in the wild of Florida. Grady and Emily go exploring and get lost in a swamp where they find a crazed white-haired man who chases them all the way home. A subsequent series of strange events lead the two children to believe that there is a werewolf in their midst and they start making accusations about who the werewolf might be.