In sixteenth-century Venice three bodies surface in the dark waters of the Canal Grande. Entrenched in a terrible war with the Turks and caught in a political struggle between power-hungry Pope Alexander VI and the newly elected Doge Loredan, the people of Venice fear that a demon has come to exact divine punishment for their sins.
Doge Loredan is determined to find the real culprit before the Pope can turn the people against him. To do so, he hires unorthodox German monk Mathias to investigate the murders. Soon Lorenzo Scarpa, a young printer and nephew to one of the victims, joins in the search. The mystery leads them into Venice’s underground printing industry, where they learn of a dangerous book hidden somewhere in the city, a book whose secrets could determine the destiny of the Republic—a book that others are more than willing to kill for.
