At Green’s Restaurant and Oyster Bar, an elegant watering hole in St. James’s frequented by inhabitants of London’s art world, the mood was decidedly funereal. They had known Gabriel Allon not as an intelligence operative but as one of the finest art restorers of his generation—though some had been unwittingly drawn into his operations, and a few had been willing accomplices. Julian Isherwood, the noted dealer who had employed Allon for longer than he cared to remember, was inconsolable with grief. Even tubby Oliver Dimbleby, the lecherous dealer from Bury Street who was thought to be incapable of tears, was seen sobbing over a glass of Montrachet he’d poached from Roddy Hutchinson. Jeremy Crabbe, the director of Old Master paintings at the venerable Bonhams auction house, called Allon “one of the greats, truly.” Not to be outdone, Simon Mendenhall, the permanently suntanned chief auctioneer from Christie’s, said the art world would never be the same. Simon had never laid eyes on Gabriel Allon and probably couldn’t pick him out of a police lineup. And yet somehow he had spoken words of undeniable truth, something he rarely did.

There was sadness, too, across the pond in America. A former president for whom Allon had run many secret errands said the Israeli intelligence officer had played a crucial role in keeping the U.S. homeland safe from another 9/11-style terror spectacular. Adrian Carter, the longtime chief of the CIA’s National Clandestine Service, called him “a partner, a friend, perhaps the bravest man I have ever known.” Zoe Reed, an anchor on CNBC, faltered while reading a scripted account of Allon’s death. Sarah Bancroft, a special curator at New York’s Museum of Modern Art, inexplicably canceled her appointments for the day. A few hours later she told her secretary she would be taking the remainder of the week off. Those who witnessed her abrupt departure from the museum described her as distraught.

It was no secret that Allon had been fond of Italy, and for the most part Italy had been fond of him, too. At the Vatican, His Holiness Pope Paul VII repaired to his private chapel upon hearing the news, while his powerful private secretary, Monsignor Luigi Donati, made several urgent phone calls, trying to determine whether it was true. One of the calls was to General Cesare Ferrari, chief of the Carabinieri’s famed Art Squad. The general had nothing to report. Nor did Francesco Tiepolo, the owner of a prominent Venetian restoration firm who had retained Allon to secretly restore several of the city’s most prominent altarpieces. Allon’s wife was from the ancient Jewish ghetto, and his father-in-law was the chief rabbi of the city. Donati placed several calls to the rabbi’s office and home. All went unanswered, leaving the papal private secretary no choice but to assume the worst.