Gangs of Athol by Clark Graham

Only one week after finishing sixth grade, Billy’s summer was already doomed. He’d been kicked out of his bicycle gang, leaving him no friends to hang out with. In a small North Idaho town, what else could he do? On top of that, his mother was more secretive than ever. Billy feared she had a boyfriend. How else to explain her hushed late-night phone calls? And who was the man watching their house from across the street? If Billy had a father, he’d feel safer, but he didn’t know who he was. His sister, Loretta, fell for the story about the stork. As the summer progressed, mysteries increased, including a mystery man parked outside the house every night and an evil looking stranger riding a motorcycle who asks about his family all over town. Mother promised “all will be revealed” when Billy is a teen, causing Billy to dread his upcoming birthday.