One afternoon, Commissario Guido Brunetti gets a frantic call from the director of a prestigious Venetian library. Someone has stolen pages out of several rare books. After a round of questioning, the case seems clear: the culprit must be the man who requested the volumes, an American professor from a Kansas university. The only problem—the man fled the library earlier that day, and after they check his credentials, it seems the American professor doesn’t exist.

As the investigation proceeds, the suspects multiply. And when a seemingly harmless theologian who’d spent years reading at the library turns up brutally murdered, Brunetti must question his expectations about what makes a man innocent or guilty.