GABRIEL knew the basics about the Nazi rape of Europe ’s art treasures during the Second World War. Adolf Hitler had dreamed of building a massive Führermuseum in his hometown of Linz and filling it with the world’s finest collection of Old Masters and Northern European art. In 1938, he initiated a secret operation code-named Sonderauftrag Linz -Special Operation Linz-to acquire art for the Führermuseum by any means necessary. During the last months of peace, his agents secretly toured the museums, galleries, and private collections of Europe, selecting works for the future museum. When war broke out, Hitler’s art thieves followed hard on the heels of the Wehrmacht. Hundreds of thousands of paintings, sculptures and objets d’art quickly vanished, many of them Jewish-owned. Thousands of works, valued at roughly $30 billion, were still missing.

Gabriel knew that Julian Isherwood could fill in the rest of the details for him. Isherwood was an above-average art dealer who’d had his fair share of triumphs, but when it came to the Nazi plunder of Europe he was something of an expert. He had written dozens of articles for newspapers and trade publications and five years earlier had coauthored a well-received book on the subject. Despite the pleas of his publisher, he had steadfastly refused to reveal his personal motivation for pursuing the topic. Gabriel was among the handful of people who knew why: Julian Isherwood had lived through it.

“In 1940, London and New York didn’t matter,” Isherwood began. “ Paris was the center of the art world, and the center of the Paris art scene was the rue de la Boétie in the eighth arrondissement. The famous Paul Rosenberg had his gallery at number twenty-one. Picasso lived across a courtyard at number twenty-three with his wife, the Russian dancer Olga Koklova. Across the street stood the gallery of Étienne Bignou. Georges Wildenstein had his gallery at number fifty-seven. Paul Guillaume and Josse Hessel were also there.”

“And your father?”

“Isakowitz Fine Arts was next to Paul Rosenberg’s. We lived in a flat above the main exposition rooms. Picasso was ‘Uncle Pablo’ to me. I spent hours at his flat. Sometimes, he’d let me watch him paint. Olga used to give me chocolate and cake until I was sick. It was an enchanted existence.”

“And when the Germans came?”

“Well, it all came crashing down, didn’t it? The invasion of the Low Countries started on May tenth. By June fourteenth, the Germans had entered Paris. Swastikas hung from the Eiffel Tower, and the German General Staff had set up shop at the Hôtel Crillon.”

“When did the looting start?”

“Two days after Hitler’s victory tour of Paris, he ordered all works of art owned by Jews to be transferred to German hands for so-called safekeeping. In reality, the plunder of France was on.”

“If I remember correctly, Hitler set up an organization to oversee the looting of France.”

“There were several, but the most important was a unit called the ERR: the Einsatzstab Reichsleiter Rosenberg. It was a formidable enterprise. It had its own intelligence service for hunting down works of art, a strike force for raids and seizures, and a staff of art historians and appraisers. My God, it even had its own carpenters for crating looted works for shipment to Germany.”

“The rue de la Boétie must have been their first stop.”

“The ERR went after the dealers and the collectors. The Rothschild collections were seized along with their residences. So were the collections of the Jewish banking magnate David David-Weill and Jacques Stern. All the Jewish-owned galleries on the rue de la Boétie were raided and their collections seized, including the inventory of Isakowitz Fine Arts.”

“Did your father manage to protect any of his works?”

“Most dealers, my father included, tried to protect their most important pieces. They hid them in remote chateaux or bank vaults or shipped them out of the country. But the unprotected works were quickly snatched up by the Germans. Before the invasion, during the drôle de guerre, my father rented a villa in Bordeaux and moved his most important pieces there. We fled there as the Germans closed in on Paris. When France was divided into the Occupied Zone and the Unoccupied Zone, we ended up on the Vichy side of the line. But in the autumn of 1940, an ERR strike force with a French police escort broke down the door of the villa and seized my father’s paintings.”

“How did the Germans find his collection?”

“He’d made the mistake of telling a French dealer what he planned to do with his paintings. The Frenchman turned over the information to the ERR in exchange for a payoff of five percent of the value of my father’s collection. C’est la vie. ”

Gabriel knew what had happened next, and he had no intention of allowing Isherwood to tell it again. Shortly after the Germans moved into the Unoccupied Zone late in 1942, the SS and their allies in the Vichy government began rounding up Jews for internment and deportation to the death camps. Isherwood’s father hired a pair of Basque smugglers to take young Julian over the Pyrenees into the sanctuary of Spain. His mother and father stayed behind in France. In 1943 they were arrested and sent to Sobibor, where they were immediately murdered.

Isherwood shivered once violently. “I’m afraid I feel a drink coming on. On your feet, Gabriel. Some fresh air will do us both some good.”

THEY walked around the corner to a wine bar in Jermyn Street and settled next to a hissing gas fire. Isherwood ordered a glass of Médoc. His eyes were on the flames, but his mind was still in wartime France. Like a child creeping into his parents’ room, Gabriel gently intruded on his memories.

“What happened to the paintings once they were seized?”

“The ERR commandeered the Musée Jeu de Paume and used it as a storage facility and sorting house. A large staff worked night and day to catalogue and appraise the massive amount of art that was falling into German hands. Those works deemed suitable for the Führer’s private collection, for the Linz project, or other German museums-mainly Old Masters and Northern European works-were crated and shipped off to the Fatherland.”

“And the rest of it? The Impressionists and the Modern works?”

“The Nazis considered them degenerate, but they weren’t about to let them get away without first extracting something in return. Most of the nineteenth- and twentieth-century works were sold off to raise cash or set aside to be used in exchanges.”

“What sort of exchanges?”

“Take Hermann Göring, for example. He owned a large hunting lodge south of Berlin called Carinhall in honor of his dead wife, a Swedish aristocrat named Carin von Fock. It contained one of the largest private collections in Europe, and Göring used his extraordinary power to enlarge it substantially during the war. He treated the storerooms of Jeu de Paume as though they were his private playground.”

Isherwood drained his glass and ordered another.

“Göring was a greedy bastard-he grabbed more than six hundred paintings from the Jeu de Paume alone-but he went to great lengths to make it appear as though his acquisitions were, on paper at least, legal purchases rather than outright thefts. If Göring wanted a work, he had it specially appraised at a ludicrously low level by a handpicked fonctionnaire. Then he would immediately take possession and promise to send the money into a special ERR account. In reality, he paid nothing for the paintings he took from Paris.”

“Did they end up in Carinhall?”

“Some, but not all. Göring shared Hitler’s disdain for Modern and Impressionist paintings, but he knew they could be sold off or traded for pieces more to his taste. One deal was carried out by Göring’s agents in Italy. In exchange for seven Italian Old Masters works and several other objets d’art, Göring handed over nine paintings seized from the Jeu de Paume. Van Gogh, Degas, Cézanne, Renoir, and Monet, just to name a few-all stolen from Jewish collections and galleries. Göring carried out several other similar exchanges involving dealers in Switzerland.”