Mark, Judy and Roger (ranging from 14 to in age) go with their mother to their grandparents farm in New England, when Daddy goes into the Navy. From the start, they notice queer happenings, --strange noises in the barn, evidence of a recent fire and a broken knife, a weird face appearing and disappearing in the woods; queer accidents involving Mark's plane models and Judy's scarecrow -- and finally the discovery of three young boys who are determined to scare the Arnolds off. The unravelling of the mystery forms the plot of the book, which is not up to the mystery standards of even this age group. Neither particularly well-written nor characterised.