Knock Knock by S.P. Miskowski
Amazon US $0.99
At the center of S.P. Miskowski's novel-length fairy tale are three restless girls, best friends stuck in the backwater of Skillute, Washington in the late 1960s. Their neighbors and families are petty or poor, or both. They warn the girls not to go into the forest. Something evil lurks there, they say. During a playful oath, the girls wander too far and their mistake unleashes a malignant spirit that terrorizes Skillute for the next fifty years.