A diverse group of nine passengers embarks on a flight from Los Angeles to Panama City aboard the airliner The Silver Queen. Among them are Judson Ellis, a wealthy young man eloping with his fiancée Alice Melhorne due to disapproving parents, and an elderly couple, Professor Henry Spengler and his wife Martha Spengler. Also on board are Tommy Mulvaney, the son of a gangster, accompanied by his escort, gunman Pete; Peggy Nolan, a woman with a shadowy past; and Vasquez, an anarchist facing extradition and a death sentence for killing a high-ranking politician, guarded by Mr. Crimp, played by John Carradine.
Their journey takes a dangerous turn when they encounter a violent storm during the night, which causes chaos aboard the plane. A loose compressed gas cylinder causes a door to open, tragically leading to the fall of Larry (the steward) while trying to secure Tommy. The plane suffers an engine failure, forcing the pilots—Joe Brooks and Bill, the pilot—to execute an emergency crash-landing deep in the Amazon rainforest. When daylight breaks, the stranded passengers realize that they are far south of rescue zones, and the nearest civilization is blocked by treacherous mountains.
The aftermath sees the survivors battling the harsh environment, with weeks passing as Bill and Joe work tirelessly to repair the battered aircraft. The ordeal profoundly impacts everyone: the Spenglers rekindle their love amid adversity, while Peggy Nolan begins opening her heart to Bill, though she confesses her sordid past. Meanwhile, Judson Ellis falls into despair, drowning his frustrations in alcohol, and Alice Melhorne begins to toughen up, developing an unexpected attraction toward Joe. The sight of their shared struggles causes Vasquez to reconsider his radical beliefs as he witnesses how the group copes with their dire situation.
Trouble arises when Mr. Crimp mysteriously disappears, and eventually, Tommy uncovers his dead body, killed by a poison dart. During a search for Tommy and Peggy Nolan, the young boy leads them to find Crimp’s corpse. Pete sacrifices himself as he shields Peggy and Tommy from native attackers, but is killed in the process. The remaining survivors manage to repair the plane sufficiently for takeoff. However, a critical issue emerges: one engine has a leaking oil line, which can only be temporarily patched and will fail after takeoff. This leaves the aircraft with a severe weight limit, capable of transporting only four adults and Tommy across the mountains.
Tensions erupt when Vasquez forcibly declares he will decide who will fly, citing his belief that since he perceives himself as doomed regardless, he has no bias. As the repairs are finalized, Professor Spengler and his wife Martha volunteer to stay behind, knowing their remaining years are limited. In contrast, Judson Ellis attempts to bribe Vasquez with money and influence, hoping to sway the decision. When the plane is ready for departure, Vasquez chooses to take both pilots, the two women, and Tommy. This decision results in a deadly confrontation where Vasquez kills Judson in a struggle, shooting him dead. The plane departs, leaving behind Vasquez and the Spenglers, who resignedly face their tragic fate as natives close in.
As the natives approach, Professor Spengler calmly warns that they must not be taken alive because they would be tortured. Vasquez deceives him, claiming there are three bullets left, then proceeds to execute both the professor and his wife before quietly awaiting his own grim destiny. The story ends on a poignant note, illustrating a harrowing tale of survival, moral dilemmas, and the dark choices made in the face of insurmountable odds.
