The Boy Lost in Plain Sight

Fifteen year-old Amelia Jamsen, just finished her freshman year at Staley high school in Missouri. But her parents recently got divorced and now it time to start new. Amelia and her mom move to Colorado. The divorce was hard on Amelia but the move it's self was a relief, having never been able to connect with anyone she met. She gets to start a new plate, but one evening she approaches an old playground and sees a boy her age sitting on a swing, they immediately connect, she finally knows what it's like to have a friend. But as the weeks pass she notices little strange behaviors coming from the boy, he's extra cautious when they are in public checking around them like someone's watching, makes up excuses to not meet her mom, and she's never once seen him at school.
What's going on with him? who is this boy? and can she really trust him?