The Beasties is by William Sleator. When Doug and his family move to a deserted farm house so his father can study fungus, they discover many of the surrounding logging camps have been vandalized and locals have lost arms, legs, eyes, and other limbs. At first he doesn't believe the stories about "the beasties", but then he and his sister are lured below ground and find themselves embroiled in a war between the humans and the "beasties". Another of Sleator's horror tales for children.
Ratings: 5th grade - 7 out of 10 - V (violence).