Nine passengers board a commercial flight from Los Angeles to Panama City: wealthy Judson Ellis (Patric Knowles) and Alice Melhorne (Wendy Barrie), eloping because their parents disapprove; an elderly couple, Professor Henry Spengler (C. Aubrey Smith) and his wife Martha (Elisabeth Risdon); Tommy Mulvaney (Casey Johnson), the young son of a gangster, and his escort, gunman Pete (Allen Jenkins); Peggy Nolan (Lucille Ball), a woman with a shady past; and Vasquez (Joseph Calleia), an anarchist being extradited and facing a death sentence for killing a high-ranking politician, and his guard, Crimp (John Carradine), who expects a $5,000 ($85,100 today) reward for delivering him. Pilot Bill (Chester Morris), co-pilot Joe Brooks (Kent Taylor), and steward Larry (Dick Hogan) comprise the crew.Chester Morris, John Carradine, Lucille Ball and Joseph Calleia in Five Came BackOn their way to Panama, a fierce nighttime storm buffets their airliner, The Silver Queen. A gas cylinder is shaken loose and knocks a door open; steward Larry attempts to close it, but falls to his death. An engine fails and the pilots are forced to crash-land in jungle terrain. In the morning the professor recognizes plants of the Amazon rainforest: the aircraft has been blown far south of where rescuers will search; the nearest civilization is across the mountains. But there is water, and enough fruit and game for everyone to live on.Weeks go by while Bill and Joe struggle to repair the damaged airliner, while the others clear a runway and lighten the aircraft by removing all unnecessary weight. The experience changes everyone. The Spenglers rediscover their love for each other. Bill warms to an appreciative Peggy, although she tells him about her sordid past. Judson falls apart, staying drunk much of the time, while Alice toughens up and begins to feel attracted to Joe. The biggest change is to Vasquez. Seeing how well most of the group have coped with their situation, he reconsiders his radical beliefs.On the 23rd day, Crimp disappears; Tommy eventually discovers his dead body. When Peggy and Pete go looking for Tommy, he leads them to Crimp's body, which has a poison dart stuck in it. Pete orders Peggy to take Tommy to safety while he covers their retreat, but he is quickly killed by unseen natives.The remaining survivors board the now-repaired airliner, but as the engines turn over, an oil leak develops. Bill and Joe patch it, but realize that their repair will fail some time after takeoff, leaving only one running engine. As a result, the aircraft can only carry four adults and Tommy across the mountains. As everyone tries to decide how to choose who must stay behind, Vasquez suddenly grabs a pistol and announces that, since he is doomed no matter what, he is the only one without bias and will make the decision. While the leak repairs are being made, he is approached by Professor Spengler, who says that he and his wife have lived their lives and should stay; then Judson tries to bribe Vasquez by offering to pay for a top lawyer.When the aircraft is ready, Vasquez announces that both pilots and both of the younger women will go along with Tommy. Judson attacks, and Vasquez shoots him dead. The airliner takes off, leaving behind Vasquez and the Spenglers. As the natives approach, Professor Spengler quietly informs Vasquez that they must not be taken alive, as they will be tortured. Vasquez lies to him, telling him that there are three bullets left. He kills the couple with his last two bullets, and then awaits his grisly fate.
Output: Question: Where does the Professor determine they have landed?, Answer: The Amazon rainforest