When Grady's family moves out of the city and into a rickety old house in Fever Swamp, both he and his sister Emily find a lot to complain about: they have no friends, no neighbors and nothing to do. Then Grady meets the only other kid around, Will Blake, who tells him the legend of the swamp and about the werewolf responsible for the mysterious disappearances of many former residents. Although Grady is afraid the legend may be true, his parents and sister refuse to believe it...until the next full moon.