All murder mysteries follow a simple set of rules. Grant McAllister, an author of crime fiction and professor of mathematics, once sat down and worked them out. But that was thirty years ago. Now he's living a life of seclusion on a quiet Mediterranean island – until Julia Hart, a sharp, ambitious editor, knocks on his door. His early work is being republished and together the two of them must revisit those old stories. Julia's come looking for answers. But now she's locked in a battle of wits with a dangerously clever adversary who wrote the book on murder...