After narrowly surviving his last operation, Gabriel Allon, the wayward son of Israeli intelligence, has taken refuge behind the walls of the Vatican, where he is restoring one of Caravaggio's greatest masterpieces. But early one morning he is summoned to St. Peter's Basilica by Monsignor Luigi Donati, the all-powerful private secretary to His Holiness Pope Paul VII. The body of a beautiful woman lies broken beneath Michelangelo's magnificent dome. The Vatican police suspect suicide, though Gabriel believes otherwise. So, it seems, does Donati.