The Prisoner’s Key In this 13th book in the Key Mystery Series, Mandy, Nick and friends are part of a research team on mysterious Alcatraz Island in California. Underneath the infamous and supposedly escape-proof former federal prison are the dark tunnels and rooms of the Citadel—a Civil War era fort—that the children are itching to explore. But they’ve been warned to not go off exploring on their own. As they work with a group of college students to clear debris out of the rooms, they encounter the ghost of a prisoner from the 1800s who pleads for help. How do you help a ghost? Meanwhile, they find a hidden room with a secret and search for a key to unlock its mystery. In the process, they also discover something shocking that will change history. The Prisoner’s Key , an exciting mystery of exploration and discovery, conflict and conspiracy, will keep 8-12-year-olds reading to the surprise ending!