PlotGlenn Ford), a small-time American gambler newly arrived in Buenos Aires, Argentina, who has a love-hate relationship with his former lover, Gilda (Rita Hayworth). When he wins a lot of money cheating at craps, he has to be rescued from a robbery attempt by a complete stranger, Ballin Mundson (George Macready). Mundson tells him about an illegal high-class casino, but warns him not to practice his skills there. Farrell ignores his advice, cheats at blackjack, and is taken by two men to see the casino's owner, who turns out to be Mundson. Farrell talks Mundson into hiring him and quickly gains his confidence. However, the unimpressed washroom attendant, Uncle Pio (Steven Geray), keeps calling him "peasant".
One day, Mundson returns from a trip with a beautiful new wife, who is none other than Gilda. Unaware that she was once Farrell’s lover, Mundson assigns Farrell to keep an eye on her. Farrell keeps track of her, his loathing for her intensifying as she cavorts with men at all hours.
Meanwhile, Mundson is visited by two German businessmen. Their secret organization had financed a tungsten cartel, with everything put in Mundson's name to hide their connection to it. However, when they decide it is safe to take over, Mundson refuses to transfer ownership to his backers. The Argentine secret police are interested in the Germans; government agent Obregon (Joseph Calleia) introduces himself to Farrell to try to obtain information, but the American knows nothing about that aspect of Mundsen's operations. When the Germans return later, Mundson shoots and kills one of them.
That same night, at Mundson's house, Farrell and Gilda describe how much they hate each other, then end up kissing. Mundson arrives at that moment, then flees to a waiting airplane. Farrell and Obregon witness its short flight; the plane explodes shortly after takeoff and plummets into the ocean. However, Mundson has parachuted to safety, thus faking his death.
With Mundson apparently dead, Gilda inherits his estate. Farrell marries her, but not out of love. He stays away, but has her guarded day and night out of contempt for her and loyalty to Mundson. Gilda tries to escape the tortured love-hate relationship, but fails. Finally, Obregon tells Farrell that Gilda was never truly unfaithful to Mundson or to him, prompting Farrell to try to reconcile with her.
At that moment, Mundson reappears, armed with a gun. He faked his death to deceive the Nazis. Mundson tells them he will have to kill them both, but Uncle Pio manages to fatally stab him in the back. Obregon shows up and confiscates the estate for the government. Farrell and Gilda are free to leave the country.
- Rita Hayworth as Gilda Mundson Farrell
- Glenn Ford as Johnny Farrell / Narrator
- George Macready as Ballin Mundson
- Joseph Calleia as Det. Maurice Obregon
- Steven Geray as Uncle Pio
- Joe Sawyer as Casey
- Gerald Mohr as Capt. Delgado
- Mark Roberts as Gabe Evans
- Ludwig Donath as German
- Don Douglas as Thomas Langford
- Lionel Royce as German
- Saul Martell as Little man
- George J. Lewis as Huerta
- Rosa Rey as Maria
- Anita Ellis, the singing voice of Rita Hayworth