All she ever wanted was her very own literary salon — and she didn’t care if she had to turn traitor to get one.

Florence Gould, the “Queen of the Riviera,” was a flapper fashion plate and a Depression-era trend-setter who parlayed her husband’s inherited fortune into a chain of casino pleasure palaces throughout France. American by birth but French to the tips of her manicured fingers, the green-eyed beauty cultivated a vast network of friends and lovers that included some of the biggest names of her day, including Charlie Chaplin, F. Scott Fitzgerald, Coco Chanel and Maurice Chevalier.

She was also a blithe Nazi collaborator who tried to launder ill-gotten wealth for Hitler’s regime and ran a Paris prostitution ring to pleasure German occupiers during World War II. She added “ownerless” art masterpieces confiscated from Jewish connoisseurs to her exquisite art collection. And after the Third Reich’s defeat, Gould’s status helped absolve her war crimes — as the international jet set politely looked the other way.

In her new book “A Dangerous Woman” (St. Martin’s Press), out now, Susan Ronald traces Gould’s amoral life and high-flying times.

Born in San Francisco in 1895 to French immigrant parents, Florence Lacaze fled the West Coast with her mother and younger sister after the 1906 earthquake leveled the city by the Bay. They settled in Paris to live in genteel poverty, leaving Florence’s newspaper-editor father behind.

She grew up coveting a place in the salons of Paris, regular gatherings of artists and writers ruled by the city’s wealthiest, wittiest women. In 1918, as a scantily clad chorus girl in the famous Folies Bergère, she schemed to reel in a rich husband who would help her join that upper crust.

Enter Frank Jay Gould, youngest son of American robber baron Jay Gould, whose share of his family’s estate would be worth about $4 billion today.

‘Everybody slept with everybody else. It was fun. It was practical.’

When they wed in 1923, they agreed that neither would give up their extracurricular sexual dalliances, forming an early open marriage. “Everybody slept with everybody else,” Florence Gould would say decades later. “It was fun. It was practical.”

As business partners, they launched a hotel and casino after spending a winter on the French Riviera. The Goulds chose the sleepy village of Juan-les-Pins, located between Cannes and Monte Carlo on the Mediterranean coast.

The Hotel Provencale, a lavish 256-bedroom Art Deco palace, immediately drew a chic crowd of entertainers, artists and writers. Rudolph Valentino, Ernest Hemingway, Pablo Picasso, Scott and Zelda Fitzgerald, Mary Pickford and Douglas Fairbanks all gambled and lounged there.

Florence Gould reveled in playing host. Chanel designed special “beach pajamas” for her that set a fashion trend in 1926. Tennis great Suzanne Lenglen gave her lessons. An intense love affair with Chaplin ended in an offer to star in his next film — which she turned down, unwilling to leave Frank and his fortune.

“It’s true, it’s true, I love money,” she confessed. By the end of the 1930s, the Goulds’ empire encompassed 50 hotels, casinos, spas and hundreds of cafes across France.

In Paris, she carried on simultaneous affairs with the American ambassador to France, William Bullitt, and with Otto Abetz, a Nazi spy. Between them, she was well aware that the continent would soon explode into war.

Yet the Goulds remained in Europe. Escaping to America would force them to cough up millions in unpaid taxes.

France fell to Germany in 1940, and Hitler’s troops occupied Paris and much of the country for four years of horror and hardship. Nearly 80,000 French Jews were deported to Nazi death camps; many more were persecuted, their property seized. Resistance fighters risked all to undermine the Axis powers. Ordinary citizens endured travel bans, food shortages and fuel rationing.

Not Florence Gould. Elegant and still beautiful at 45, she used sex and charm as her currency, trading them for favors and luxuries that let her sail through the war years unscathed.

She slept with Helmut Knochen, the city’s top Gestapo commander, and entertained his boss Carl Oberg, the notorious SS and police leader. The head of the city’s Abwehr, or military-intelligence service, was another of her lovers. She was devoted to Ludwig Vogel, a black marketeer and undercover SS agent.

Her new friends-with-benefits tipped her off to auctions where she bid against Hitler’s own art dealers to acquire works that had been looted from Jewish collectors. She snapped up Impressionist and modern canvases deemed too “degenerate” for the Fuhrer’s tastes.

With influential fashion editor Marie-Louise Bousquet, Gould set up the “souris gris” — gray mouse — prostitution network. Their “mice,” former society women, served as high-class call girls for the Nazi leadership in exchange for black-market goods.

The occupiers provided all Gould needed to shrug off the war’s indignities: unlimited gasoline and travel passes that let her visit her husband, still in the Riviera, whenever she wished; truckloads of coal to keep her warm while the rest of Paris shivered; even an exemption from the 1942 round-up of expatriate American women that sent hundreds of them to an internment camp for months.

With the treats the Nazis allowed her, she achieved her girlhood dream of establishing a trend-setting literary salon, enticing prospective guests with real coffee, gourmet chocolates and roast beef.

In 1944, as the successful D-Day invasion foretold an Allied victory, Gould joined a Nazi money-laundering scheme meant to funnel over a billion francs of ill-gotten wealth out of Europe before Hitler’s defeat. She fronted a new bank, set up in neutral Monaco, to provide a safe haven for funds that Nazi fugitives could use to start new postwar lives.

US authorities froze the assets — and launched a treason probe into Gould’s actions. But through four years of review by French and American investigators, she played the victim, insisting that she only went along with the plot when the Nazis threatened to send her beloved Frank to the camps. A French court ruled in 1948 that her criminal complicity could not be proven.

“I have slept with the Dear Lord, and the Dear Lord loves me,” as she liked to say.

After the war, her weekly salon rolled on, its dark origins conveniently forgotten by Salvador Dali, André Gide, Jean Cocteau and other guests. She became a generous philanthropist, gifting two rare medieval tapestries and “The Terrace at Vernonnet,” a painting by modernist master Pierre Bonnard, to New York’s Metropolitan Museum of Art.

By the time of her death in 1983, at age 88, Gould owned an $8 million collection of jewels, including the fabulous 31.35-carat Victory Diamond and a spectacular three-strand pearl necklace that had been her signature accessory. Her 180 artworks, including paintings by van Gogh, Renoir, Degas and Monet, sold at auction for $34 million in 1984.

The cash established the Florence Gould Foundation, a New York-based nonprofit that continues to fund artistic and cultural programs.

Today, the Bonnard hangs in a gallery named in Gould’s honor at the Met on Fifth Avenue. The French Institute Alliance Francaise’s Florence Gould Hall on East 59th Street, a film and theater venue, is another legacy.

Florence Gould herself is interred in the Gould family mausoleum at Woodlawn Cemetery in The Bronx, a miniature Parthenon guarded by a weeping beech that the Parks Department has enshrined as one of 65 official “Great Trees of New York City.”

“Florence was une originale . . . someone you could love and dislike in equal measure,” Ronald concludes. And, in the end, a New Yorker, like her or not.

Susan Ronald will be in conversation with author Meryl Gordon at Shakespeare & Co., 939 Lexington Ave., on Monday, Feb. 26 at 6:30 p.m.