Jean-Paul Fontanon, a boy from Berlin who everyone calls "Jampoll," spends every summer in his grandparents' village. But this year, everything is different. Jampoll's grandfather appears upset and fearful of something, often disappearing into his room or writing things in a notebook. 

This strange behavior seems to be somehow related to the friendly Mr. Kohlweis, a stranger who has only been in town a short time. Jampoll and his friends slowly uncover secrets from the past which connect these two men to each other and to Owl's Hole, a swamp which everyone says is haunted...