Katie Connors (Jane Greer), on the editorial staff of Sight magazine, journeys to San Marcos, a remote Mexican fishing village, seeking novelist and adventurer Mike Latimer (Richard Widmark), who has abandoned writing "at the peak of his fame" and dropped from sight. She soon learns that he is indeed there, indulging in drinking, fishing, hunting, and flying his aircraft. Katie contrives to meet him, pretending not to know his identity, but Latimer easily sees through her clumsy denials and is immediately attracted to her. Over the next several days they enjoy each other's company, but Katie may be falling in love with him and conceals the real reason she is there.

After Latimer explains that his wife was the muse behind his literary success, and that he quit writing because she left him to be with his best friend, Katie decides to go back to New York. Latimer offers to fly her to Mexico City and asks Katie to write down her address to keep in touch. During the flight, the magnetized notebook in Katie's purse affects the aircraft's magnetic compass and they find themselves lost over jungle. The aircraft runs out of fuel and Latimer crash-lands in a small clearing. Knocked unconscious, he wakes up to find himself in a bed in the main house of a hacienda.

Katie introduces him to their rescuers, an Englishman named Browne (Trevor Howard) and the Dutch archaeologist Dr. van Anders (Peter van Eyck), who live on the estate with Jan (Carlos Henning) a third European. Latimer feels that he once met the cordial Browne, a big game hunter himself, but cannot place it. The more suspicious and secretive Anders asks about a rifle bullet that Latimer always carries with him, which Latimer relates is a souvenir and good luck charm from the D-Day invasion, a time when his courage failed him. Almost immediately the couple senses that things are not as they appear.

Browne keeps a pack of savage dogs to prowl the estate and control the local populace; when Latimer goes to examine the condition of his aircraft, it has disappeared; Browne claims he has no contact to the outside world and Katie doubts that Anders is really an archaeologist. However friction develops between them when a newscast on the radio announcing their disappearance reveals Katie's identity and original purpose. Katie tries to persuade Latimer that she no longer intends to write the story but he rebuffs her.

That night, Latimer finds a storeroom containing military gear with Nazi markings, items from his missing aircraft supposedly stolen by the local Indians, and a cabinet of hunting rifles. The barking of the prowling dogs awakens Browne and Anders, and Latimer overhears them talking in German. He tells Katie what he found and warns her that they need to work together to try to escape. They discover that Browne has been concealing from them, his own "flyable" aircraft.

Latimer finally realizes it is Browne's voice he recognizes, and that he is an infamous turncoat who during the war broadcast Nazi propaganda from Berlin to Britain after he had married a German girl. The Englishman admits the truth and adds that his wife was Anders' sister, killed in a British air raid. Latimer tries to bargain for Katie's release but to no avail. Latimer realizes Anders is a German war criminal who massacred an entire village and intends to kill them. He and Katie try to steal the aircraft, but when Jan shoots at them, they flee into the jungle.

Browne, leading Anders, Jan and the dogs, follows their trail, failing to catch them the first day when a group of wild pigs attack the dogs. The next day, the wilderness-wise Latimer rigs a crude booby trap that kills Jan. With Katie nearing exhaustion, Latimer contrives to double back, and when Browne and Anders find Jan's dead body, they realize that the aircraft has been left unguarded. Stopping for the night, Latimer starts to cover Katie with his jacket and finds that she wrote down the office address of Sight magazine as her own, proving that she had been truthful about her feelings.

They reach the hacienda just ahead of their pursuers and barricade themselves in the chapel. Anders pretends to negotiate with Latimer and shoots through the door. Latimer ridicules him and when Anders goes to bring workers to break down the door, he is forced to lock up the dogs to get their cooperation. Browne fears the fanatical Nazi and offers to shoot Anders if Latimer flies him to South America. Latimer refuses and uses the bullet hole in the door as a makeshift gun barrel for his lucky bullet, striking the primer with a chisel and fatally shooting Browne. Latimer and Katie take off in Browne's aircraft, killing Anders with the propeller when he tries to block their path. They manage to safely escape.