Case of the Bookstore Burglar #3

Pete and Penny live above Pizzarelli''s, the family pizza parlor, in the town of Redville. A bookstore opens next door and strange things start happening there - bookshelves collapse, the fire alarm goes off, books disappear! Is someone trying to sabotage the new bookstore? When a secret message appears in the wall between the two stores, Pete and Penny start to puzzle it out. They need your help!