Dani is spending the summer in Three Rivers, California when she meets hobo Mott Simon. At first Dani is afraid of Mott, but when he is accused of murder Dani sets out to prove otherwise. She confronts a skeptical sheriff, a dispassionate prosecutor, and a patronizing defense attorney. The clues point toward Ardy, an autistic boy who may have witnessed the murder, and has disappeared. Dani notices parallels between her mystery and To Kill A Mockingbird, a book the town's librarian pressed upon her. She begins to realize you can't judge a book by its cover.