In October 1502 the powerful Cesare Borgia was preparing to invade the Florentine Republic. Niccolo Machiavelli, an official of the Republic, is sent to Borgia's court to spy on him. 33 years old, he has a nice pen, but he's not famous. He cheats on his wife avidly, and he's deep into debts. He's seen as trusted and useful, but he's kept on the sidelines.

A complex relationship is created between Machiavelli and Borgia. The Duke needs someone to write a biography to respond to the many "slanders" circulating about him and he chooses Niccolo to do it. And so Machiavelli not only gains wider access to Borgia's secrets, but also those of Dianora Mambelli, a young woman forced by the Borgias to stay by his side. Attending to both executioner and victim, listening to the Duke's reflections and discovering the hidden truths that Dianora reveals to him, transform Machiavelli and give him the insight that will allow him to become a great writer. And put his own life at risk.

The Prince, written years later, was published posthumously. Thanks to it, the writer they all thought mediocre will prove to be a genius, and Cesare Borgia will survive forever, just as he wanted.