When an airplane lands in Los Angeles after sending a radio request for police and medical aid, one of the passengers, matronly Mrs. Judd, tells Police Inspector Bruce what happened: After taking off from New York's La Guardia Airport, the plane makes a brief stop in Chicago, where co-pilot Bill Arthur joins the crew. The plane leaves Chicago, and while most of the passengers are sleeping, a passenger named Middleton is strangled in his seat. When the stewardesses discover Middleton's body in the wardrobe compartment, two men named Murray and Carter brandish guns and begin to rob all of the passengers. They take a jewel case from a diamond merchant named Sebastian, but Mrs. Judd becomes suspicious of Sebastian when she notices that the case is empty. Murray and Carter then break the radio equipment and other instruments in the cockpit, shooting and wounding Bill in the process, before bailing out with their loot. Mrs. Judd shares her suspicions with pilot Ned Johnson, explaining that the robbers knew Sebastian was carrying his valuable merchandise on his person. Sebastian enters the cockpit with a gun and admits that he staged the holdup, hiring Murray and Carter to pretend to steal his jewels. He tells Ned that he strangled Middleton, an insurance investigator assigned to keep an eye on the jewels, and that he gave Murray and Carter defective parachutes so that they would fall to their death. The two men fight as the plane veers out of control, but Ned finally subdues Sebastian, and Bill uses a makeshift radio to contact the airport. Back in Los Angeles, Ned has just finished giving his account of the events to the police. Mrs. Judd then surprises everyone by revealing that she has come to California to attend a reunion of beauty contest winners, and that she had the distinction of being Miss Coney Island of 1918.