Twelve-year-old Pete Collison is a regular kid who loves Sam Spade detective books and radio crime dramas. When an FBI agent shows up at Pete's doorstep accusing his father of being a communist, Pete finds himself caught in a real-life mystery. Could there really be commies in Pete's family? At the same time, Pete's class turns against him, thanks to similar rumors spread by his teacher. Even Kat, Pete's best friend, feels the pressure to ditch him. As Pete follows the quickly accumulating clues, he begins to wonder if the truth could put his family's livelihood, and even their freedom, at risk forever.