On a royal whim, Ludovico Sforza, the Duke of Milan, orders a living chess game to be enacted by members of his own court. Court Engineer Leonardo da Vinci conjures the spectacle in a single night, but his latest success turns bitter when one of the "pieces"-the Duke's ambassador to France-is murdered. Given the brutal climate of court politics, even the Duke's closest advisors are suspect. As an outsider, Leonardo is the only man Sforza can trust to conduct the investigation. With his scrupulous eye for detail, and young apprentice Dino gathering information unnoticed, Leonardo uncovers a vile nest of secrets-while danger, like an ill humor, rises to the surface. But the most surprising secret of all may be the true identity of his most talented, most trusted apprentice.