Book Carly Anne West, Tim Guy. Hello Neighbor. Book 3. Buried Secrets

Product description from producer

Niki Roth should be happy – he has finally proven that his best friend, Aaron Peterson, along with his younger sister, Mia, mysteriously disappeared. Moreover, the police are actually doing something: they have plastered the town with missing children posters and organized search groups on weekends. But Niki's attention is focused on the house across the street, especially since he hears a frantic SOS coming from Aaron's room in the Petersons' house. Given the events of the winter and having listened to his parents' advice, Niki's friends refuse to help him investigate the Petersons' mystery. If Niki wants to find out what is happening in the neighbor's house, he will have to do it on his own.