He discovers she is living with the Spanish-born nursing student/model Mia and has a lover, whom she quickly discards when Guy moves in. The trio are enjoying their unusual living arrangement, but world events are beginning to affect their existence. It is the height of the Spanish Civil War, and idealistic Guy, a long-time supporter of the army of the Second Spanish Republic, is determined to do what he can to help them as Francisco Franco's fascists gain strength. Mia, too, is anxious to come to the aid of her native land. Gilda, however, has no interest in politics or anything else that might disrupt her life of luxury, and pleads with the two to ignore the conflict, but they feel compelled to act and depart for Spain.
Guy becomes a soldier, while Mia tends to the wounded. They cross paths one night and, before making love to Guy, Mia confesses she was Gilda's lover. In the morning, her ambulance is destroyed by a land mine, and after laying her to rest, Guy returns to Paris, where he is ignored by Gilda, who feels his abandonment of her was a form of betrayal.
Six years later, Guy is working as a spy with the underground in occupied Paris under the auspices of British intelligence. He learns Gilda has taken Nazi Major Franz Bietrich as a lover and visits her in their old apartment, where the two make love. The following morning she tells him their affair is over and the two never can see each other again. D-Day is approaching, and Guy throws himself into his work. One day he arrives at a café to meet a contact, but instead is approached by Gilda, who has overheard her German lover's plotting a trap and has come to help him escape in cleric's clothing she has concealed in the restaurant's washroom. That night, he and his associates destroy a rail station, but only Guy manages to elude the German soldiers.
Guy returns to London, where he discovers Gilda joined the Resistance a few years earlier. With the occupation of Paris having come to an end, he realizes the locals, who long regarded Gilda as a Nazi sympathizer and traitor, will seek revenge for what they perceive to be her lack of loyalty and patriotism. As he returns to Paris to find her, Guy is unaware Bietrich has been killed in Gilda's apartment and she has been taken captive by a mob intent on avenging the deaths of their loved ones.
The soundtrack included "Parlez-moi d'amour" by Jean Lenoir, "Blue Drag" by Josef Myrow, "Minor Swing" by Stéphane Grappelli and Django Reinhardt, "Big Jim Blues" by Harry Lawson and Mary Lou Williams, "La rumba d'amour" by Simon Rodriguez, "Vous qui passez sans me voir" by Charles Trenet and Jean Sablon, "My Girl's Pussy" by Harry Roy and performed by John Duiganand "La litanie à la vierge" by Francis Poulenc.
The film opened on ten screens in the US and earned $46,133 its opening weekend. It grossed a total of $398,278 in the US and $2,958,074 in foreign markets for a total worldwide box office of $3,356,352 .
Roger Ebert of the Chicago Sun-Times said the film "is silly and the plot is preposterous, but it labors under no delusions otherwise. It wants to be a hard-panting melodrama, with spies and sex and love and death, and there are times when a movie like this is exactly what you feel like indulging."
In the San Francisco Chronicle, Walter Addiego called it "a glossy, stiff melodrama . . . a mixture of Casablanca and Cabaret, or possibly Hemingway and Henry Miller, and finally, it doesn't work, in part because the erotic content seems self-conscious and force-fit. In fact, if not for the presence of Charlize Theron, it's hard to imagine this film would have attracted anywhere near the kind of attention it's gotten . . . she's not at all bad, but her role as a young American heiress and libertine feels recycled from scores of other movies."
Peter Travers of Rolling Stone awarded it one out of a possible four stars and described it as "a World War II melodrama of epic silliness and supreme vapidity . . . This spark-free film has no place to go on [the cast's] resumes except under the heading of Cringing Embarrassment."