On the evening of June 13, 1940, as German troops prepare to march into Paris, Frank Meier stands behind the bar of the Petit Bar at the Hôtel Ritz on the Place Vendôme. His last customer, Otto von Habsburg, the deposed heir to the Austro-Hungarian Empire, embraces him and flees to Washington. Austrian-born and celebrated for his cocktail artistry, Frank has run the bar since 1921. Beneath his composed exterior, he harbors a dangerous secret: He is a Jew, the son of Polish-Jewish workers who emigrated to the Austrian Tyrol and destroyed all evidence of the family's heritage. His father had him baptized Catholic, refused circumcision, and forbade any connection to Judaism. Frank left home at fourteen, worked his way up through New York's hotel bars, returned to Europe, and served in the French Foreign Legion at Verdun during World War I. He was later hired to open the Ritz's cocktail bar, where he achieved legendary status.
When the Germans occupy Paris, the Ritz receives special status as a middle ground for officers and civilians because of its Swiss ownership. Frank's staff is reduced to Georges Scheuer, his comrade from the Great War, and Luciano Baresi, his young Italian apprentice. Luciano is secretly Jewish, sent to France by his mother to escape Mussolini's racial laws; Frank has provided him with a forged Swiss passport. Colonel Hans Speidel, a German officer Frank knows from before the war, becomes a regular, while Charles Bedaux, a wealthy French-American businessman and Nazi sympathizer, celebrates the new order. Signs in Paris parks reading "NO JEWS ALLOWED" remind Frank of the danger closing in.
Marie-Louise Ritz, the elderly widow of the hotel's founder and Chair of its Board of Directors, returns from Switzerland and orders Frank to lure back Parisian artists and intellectuals. Frank persuades Sacha Guitry, the celebrated playwright, to return, and soon other luminaries follow. Reichsmarschall Hermann Göring, one of Hitler's closest allies and supreme commander of the Luftwaffe (German air force), moves into the Imperial Suite, where his extravagant habits strain the hotel's resources.
Frank's deepest preoccupation is Blanche Auzello, the wife of Ritz manager Claude Auzello. Years earlier, Frank helped forge identity papers to conceal Blanche's Jewish maiden name so Claude could marry her without jeopardizing his career. Frank harbors an unrequited love for Blanche. When the Auzellos return, Blanche hides in her apartments, going through morphine withdrawal. She eventually comes to the bar one night, terrified by a Nazi decree requiring all Jews to register with police. Frank reassures her that her forged papers are solid.
The Widow's deputy manager, Monsieur Süss, discovers that Blanche is Jewish and that Frank was involved in the forgery. Rather than expose them, Süss proposes a deal: He will keep quiet if Frank procures forged passports and safe-conduct passes. Süss needs these documents to deal directly with Jewish families selling art to satisfy Göring's appetite for looted masterworks. Frank contacts Fersen, a Scandinavian diplomat, who supplies the forgeries. Over the following months, they help some thirty Jews escape. Süss also reveals a secret tunnel connecting the Ritz basement to the Jeu de Paume gallery in the Tuileries and leaves a red silk scarf in a hidden cabinet as a signal: If the scarf disappears, Süss has fled safely.
As persecution intensifies, Blanche asks Frank to help an elderly Jewish man named Joachim Ruderman escape France. Frank agrees, paying for the passport himself. Blanche's recklessness, however, increasingly puts everyone at risk. She is arrested by the Gestapo after shouting anti-German insults at Maxim's restaurant but is released after three days. She later hides a wounded British pilot in the Ritz attic, and Frank procures false papers to smuggle him out. Claude, meanwhile, secretly feeds intelligence to the British by relaying German officers' movements through telephone calls disguised as food orders.
In July 1942, the massive Vel d'Hiv roundup sees at least ten thousand Jews, including children, arrested by French police. Frank watches in horror. By early 1943, his son Jean-Jacques and niece Pauline Neumayer arrive from Nice to live with him.
Blanche is arrested a second time, accused of leaving the Ritz kitchen lights on to guide British bombers. She is sentenced to ten months for consorting with communists, based on her association with Lily Kharmayeff, her close friend and a former Russian ballet dancer connected to Moscow. Süss warns Frank that the Gestapo is investigating him, then disappears through the tunnel. Frank agrees to host a reception for Henri Lafont, a French gangster promoted to SS commander, to demonstrate loyalty and deflect suspicion.
Inga Haag, a young German woman who introduces herself as the niece of Admiral Canaris, head of German military intelligence, becomes a regular at the bar. She reveals she is serving as a go-between for General Carl-Heinrich von Stülpnagel and asks Frank to act as their dead letter box, passing notes containing poems and cryptic messages.
The danger peaks when someone at the hotel denounces Luciano to the Gestapo. Georges warns Frank, who leads the boy to the secret tunnel, gives him money, and instructs him to flee to Biarritz and eventually North Africa. Luciano pries open the stuck door with his pocketknife and disappears. Frank is subsequently interrogated by the Gestapo, who question whether he himself is Jewish. He maintains his cover, and the interrogation ends with an invitation to serve cocktails at a Gestapo officer's wedding.
By early 1944, Frank is emotionally shattered. Hans Elmiger, the hotel's deputy manager, reveals he has known about the forged papers operation all along. Blanche is released, emaciated and barely recognizable. She tells Frank she endured sleep deprivation, beatings, and near-drowning but never broke. Frank obtains a forged Swedish passport for her to escape to America, but she changes her mind, insisting she belongs in Paris.
On July 19, Inga arrives in a panic and tells Frank to stop acting as dead letter box: The conspirators fear exposure. Frank faints, realizing he has been an unwitting participant in a plot to assassinate Hitler. The next day, Speidel arrives and receives a phone call confirming the attempt has failed. Stülpnagel, believing Hitler dead, had already arrested over a thousand SS officers in Paris. Speidel flees. Frank barricades himself in the bar for four days. Captain Ernst Jünger, a celebrated German writer, visits for a final farewell and advises Frank to take a room. Frank sleeps in a Ritz suite for the first time in his life.
As liberation approaches, Elmiger proposes that Frank secretly reopen the bar for remaining Germans while appearing closed. Blanche, arrested a third time with Lily at the Café de Flore, is released on the eve of liberation. She is skeletal, her head shaven, her arm broken. She confesses that under torture she told the Gestapo everything, including Frank's role in the forged papers. Frank kisses her forehead, accepting that friendship is all they will ever share.
On August 24, the bells of Notre-Dame announce the Allied entry into Paris. Elmiger and Frank burn four years of hotel registers while preserving envelopes left by Süss containing jewelry entrusted to him by Jewish families. On August 25, Ernest Hemingway, the American writer and longtime Ritz regular, throws open the bar door, greeting Frank as though no time has passed.
An appendix reveals the fates of the novel's key figures. Stülpnagel is executed for his role in the assassination plot. Speidel survives and continues his military career. Guitry is twice acquitted but remains tarnished by suspicions of collaboration. Blanche never recovers from her imprisonment; on May 29, 1969, Claude shoots Blanche before taking his own life. Frank is charged with profiting from the Occupation and apparently secures his release through a large payment. He dies in 1947 under unclear circumstances.