In 1940, as German troops near the outskirts of Paris, France, Samuel L. Jacobowsky, a Polish Jew who has been fleeing the Germans since their conquest of Poland, plans his next escape. As the resourceful Jacobowsky contemplates how to reach the Spanish border, Dr. Szicki of the Polish Embassy arrives at the hotel in which Jacobowsky is staying to confer with Col. Prokoszny, another guest at the hotel. When Szicki gives the Polish colonel a coded message to deliver to the Polish Embassy in London, England, the blustery, pompous colonel eagerly embraces his chance to “get into the war.” After the taxi hired to drive the colonel to St. Jean de Luz on the Spanish border, where he is to rendezvous with a London-bound submarine, is damaged in a collision, the colonel orders his aide Szabuniewicz to find him another vehicle. At the hotel café, Jacobowsky, who lived in the small Polish village in which the colonel’s family were the reigning aristocrats, tries to enlist the colonel in a scheme to requisition an automobile, but the officer rejects his proposal. When Jacobowsky purchases one of the few remaining automobiles in Paris, a Rolls Royce owned by the Baron Rothschild, the anti-Semitic colonel refuses to ride with him and confiscates the car for himself. Jacobowsky has shrewdly emptied the gas tank however, and makes a bargain with the colonel to provide gas in exchange for safe passage to the border. When the colonel turns north instead of south, and heads toward the German-occupied city of Reims, Jacobowsky becomes alarmed but the colonel insists on continuing onto Reims to pick up his fiancée, Suzanne Roualet, before leaving the country. Meanwhile, a German officer, Maj. von Bergen, arrives at the restaurant Suzanne owns in Reims and makes lewd suggestions to her, but his crude overtures are interrupted when he is summoned to headquarters. Soon after, the colonel, Jacobowsky and Szabuniewicz arrive at the restaurant, and when the colonel begins to serenade Suzanne, she runs out the door and into his arms. As Suzanne and the colonel retire to her boudoir, Jacobowsky makes a deal with some French soldiers to trade the colonel’s stash of vodka for gasoline. Later, with their gas tank now full, the four fugitives head for the South of France. As they pass columns of fleeing refugees, a French officer warns them that Paris has fallen and the Germans are looking for the colonel. When Jacobowsky suggests that the colonel exchange his uniform for civilian garb, the officer adamantly refuses. Now hungry and nearly out of gas, they camp in a market-place with the other refugees. The ever-resourceful Jacobowsky then goes to the town’s castle, and upon learning that the caretaker is a monarchist, convinces the man that the colonel is the Pretender to the Throne and is to be crowned King of France. When the caretaker invites them to stay and gives them a royal welcome, Suzanne praises Jacobowsky’s ingenuity, thus arousing the colonel’s jealousy. After Suzanne and the colonel argue over Jacobowsky’s virtues, the colonel grabs some bottles of wine and storms out of the room. Suzanne then flirts with Jacobowsk and realizes that he has fallen in love with her and coaxes him to dance. The colonel, now drunk, bursts into the room, and seeing them dancing, challenges Jacobowsky to a duel. Jacobowsky rashly picks up a sword and declares his love for Suzanne, causing the colonel to chase him into the cellar. The colonel calms down, however, when Jacobowsky finds a cask of rare brandy and offers his adversary a drink. As the colonel drunkenly caterwauls, German soldiers arrive to commandeer the castle. Jacobowsky, Suzanne and Szabuniewicz lead the drunken colonel up the stairs and, after dressing him in civilian clothes, escape out the back door and head for St. Jean de Luz. When the colonel, hung over and in shock from being stripped of his uniform, drives the car into a German tank, the four are taken to headquarters for questioning. There, Suzanne is greeted by von Bergen, who asks them if they know Prokoszny. To protect the colonel’s identity, Jacobowsky lies that his male travel companions are Polish relatives. When Suzanne appeals to the major to help them reach the border, he releases them. Sensing that the colonel has been deeply humiliated by the turn of events, Jacobowsky decides that the time has come to leave the group. While hitchhiking along the roadside, Jacobowsky is picked up by a carload of nuns who drive him to St. Jean de Luz. As Jacobowsky approaches the border crossing, his passport is confiscated and he is arrested by the Germans. At headquarters, a German officer questions Jacobowsky about the colonel’s destination. When Jacobowsky refuses to cooperate, the officer releases him and threatens to have him tortured at eight p.m. that night unless he comes forward with the information. Meanwhile, the colonel arrives at St. Jean de Luz and learns from his contact that Jacobowsky has been arrested. Although the contact implies that Jacobowsky has betrayed him, the colonel senses that Jacobowsky is in danger and goes to his aid. As the hour nears eight, Jacobowsky sits in the town square, contemplating suicide. Just as he is about to swallow a capsule of poison, the colonel drives up in his Rolls Royce and embraces him as a “comrade-in-arms.” When Jacobowsky begs the colonel to leave, the colonel assures him that Suzanne is in possession of the documents and will complete his mission. Knowing that the Germans are watching them, the colonel begins guzzling brandy and instructs Jacobowsky to devise an escape strategy. After some thought, Jacobowsky tells the colonel to drive to the convent. The Germans follow and watch as the Rolls Royce pulls into the convent gates and, moments later, drives out. When the Germans stop the Rolls they discover it is being driven by the Mother Superior. Meanwhile, Jacobowsky and the colonel peddle a bicycle to their rendezvous with the submarine. When the colonel arrives, the sub captain informs him that he has room for only two passengers. After Suzanne insists on staying behind, the colonel orders Szabuniewicz to take care of her and promises to return one day. Once Jacobowsky and the colonel are on board the submarine, the colonel panics, thinking that he left the papers behind. Jacobowsky smiles and gives him the envelope entrusted to him by Suzanne.