Bruised and war-weary following his secret war to bring down a terrorist mastermind, Gabriel Allon returns to Rome to restore a Caravaggio masterpiece. But one morning Gabriel is summoned by his friend Monsignor Luigi Donati, private secretary to the Pope.The body of a woman lies beneath Michelangelo's magnificent dome. Donati calls upon Gabriel to use his experience to pursue the truth – was it suicide, or something more sinister? Gabriel discovers that the woman revealed a dangerous secret that threatens powers beyond the Vatican.