The malice of fortune - Michael Ennis

Against a teeming canvas of Borgia politics, Niccol Machiavelli and Leonardo da Vinci come together to unmask an enigmaticserial killer, as we learn the secret history behind one of the most controversial works in the western canon, The Prince...
When Pope Alexander dispatches a Vatican courtesan, Damiata, to the remote fortress city of Imola to learn the truth behind the murder of Juan, his most beloved illegitimate son, she cannot fail, for the scheming Borgia pope holds her own young son hostage. Once there, Damiata becomes a pawn in the political intrigues of the pope's surviving son, the charismatic Duke Valentino, whose own life is threatened by the condottieri, a powerful cabal of mercenary warlords. Damiata suspects that the killer she seeks is one of the brutal condottierri, and as the murders multiply, her quest grows more urgent. She enlists the help of an obscure Florentine diplomat, Niccol Machiavelli, and Valentino's eccentric military engineer, Leonardo da Vinci, who together must struggle to decipher the killer's taunting riddles: Leonardo with his groundbreaking "science of observation" and Machiavelli with his new "science of men." Traveling across an Italy torn apart by war, they will enter a labyrinth of ancient superstition and erotic obsession to discover at its centera new face of evil-and a truth that will shake the foundations of western civilization.