Gabriel Allon, art restorer and spy, is recovering from a grueling showdown with a Palestinian master terrorist, when a figure from his past arrives in Jerusalem. Monsignor Luigi Donati is the private secretary to His Holiness Pope Paul VII, and a man as ruthless as he is intelligent. Now, however, he has come to seek Allon's expertise. Allon reluctantly agrees to help and soon begins to unravel a conspiracy of lies and deception that could only lead to one terrifying outcome: the most spectacular assassination ever attempted.