Legendary spy and art restorer Gabriel Allon is in Venice repairing an altarpiece by Veronese when he receives an urgent summons from the Italian police. The eccentric London art dealer Julian Isherwood has stumbled upon a chilling murder scene in Lake Como and is being held as a suspect. To save his friend, Gabriel must track down the real killers and then perform one simple task: find the most famous missing painting in the world. The dead man is a fallen British spy with a secret: he has been trafficking in stolen artworks and selling them to a mysterious collector. Among those paintings is the world's most iconic missing masterpiece: Caravaggio's glorious Nativity with St. Francis and St. Lawrence. Gabriel embarks on a daring gambit to recover the Caravaggio and learn the identity of the collector. At his side is a brave young woman who survived one of the worst massacres of the twentieth century.