When a flight from Washington, D. C. crash lands and its crew and passengers are discovered missing, Inspector Timothy Donovan and his assistant, Bates, are called to investigate. Later, all the passengers except for industrialist Stanley Harris Palmer and his assistant, Wally Fairchild, are found stranded at a rest stop. When Palmer's daughter Nancy receives a note demanding money for her father's return, she seeks out Tom Lawrence, the debonair sleuth known as "The Falcon." Tom proceeds to the airport and is examining the shank of a lock found in the plane's cabin when he is approached by another woman, who identifies herself as Fairchild's niece Iris. After showing Tom a ransom note ordering Nancy to leave $25,000 at a drinking fountain on Park Road, Iris tells the detective that she suspects Nancy's fiancé, Ken Gibson, of informing the kidnappers that Fairchild was carrying $100,000 in securities. Tom then accompanies Iris and Nancy to the Palmer house and there questions Ken about the ransom note. The next day, Tom is horseback riding in the park with his fiancée, Texan Bonnie Caldwell, when he sees Nancy leave a box by the drinking fountain. When two men collect the box, Tom follows their car on horseback and glimpses their license plate number. Tracing the plate to Morley's antique store, Tom goes there that night and meets Morley, who shows him the ransom box, which is filled with shredded paper. Morley explains that he read of Palmer's kidnapping in the paper and decided to use it to collect the gambling debt owed to his sons by Ken. Just then, Donovan, who has followed Tom to the store, arrives with news that Palmer has returned home alive. Tom and Donovan proceed to the Palmer house, where Palmer explains that he and Fairchild stayed onboard the plane while the others passengers deplaned. Two strangers bearing guns then boarded the plane and, after robbing Palmer at gunpoint, ordered him to parachute from the plane while the pilot set the controls on automatic. Palmer continues that the men took him to a farm house from which he later escaped. Iris reacts to Palmer's story by accusing him of cheating her uncle and then storms out of the room. As Tom and Bonnie leave the Palmer house during a dim-out, Morley's son Georgie forces them into his car and drives them to the antique store. When Morley demands the return of the ransom note, Tom switches on the store's neon sign. The lights attract a crowd and soon the police are pounding at the door to arrest Morley. Tom then goes to question Ken and Nancy at the salvage depot where they are sorting junk. In a pile, he finds the mate to the lock shank from the plane's cabin. When Nancy tells Tom that Iris delivered the junk, he begins to suspect that her uncle is involved in Palmer's kidnapping. Tom then asks Bonnie to search the Fairchild apartment while he keeps Iris occupied at a roller rink. After the skaters collide while playing crack-the-whip, Tom slips out of the rink and returns to Iris' apartment to meet Bonnie. When Iris returns, Bonnie becomes jealous and throws a vase at Tom. Among the glass shards, Tom finds the missing securities and turns them over to Donovan. The inspector is on the verge of arresting Fairchild for their theft when a call comes from the state troopers that the pilot's and Fairchild's dead bodies have been found in a field. Suspecting that Morley, who has been released from jail because of insufficient evidence, is involved in the crime, Tom returns to search his store. Tom is looking for Fairchild's briefcase when Iris enters and admits that the lock, which she found in Morley's store, came from her uncle's briefcase. Just then, Morley appears and Tom accuses him of sending the ransom note before the kidnapping was made public, thus proving that he is involved in the crime. As they talk, a man sneaks into the store and fires a gun at Morley, and in the confusion, the storekeeper disappears. Tom and Iris then visit the Palmer house, where the detective calls Donovan to warn him of an impending murder. When Tom sees Morley climb the stairs to Palmer's den, he follows him. After Morley leaves the room, Tom and Iris discover Fairchild's briefcase hidden behind a shelf of fake books. Inside the case, they discover a government questionnaire proving that Palmer cheated Fairchild out of the business. Tom then reconstructs the following story of the missing passengers: Palmer was alone on the plane, filling out the questionaire when Fairchild returned. Realizing that the document provided proof of Palmer's guilt, Fairchild locked it in his briefcase. In his struggle to gain control of the briefcase, Palmer shot Fairchild and then ordered the pilot to take off. After killing the pilot and dumping the bodies, Palmer parachuted from the plane and went to Morley's, where he broke the lock off the briefcase. Tom's story is interrupted by a noise from the closet, and when he opens the door, he finds Ken locked inside, having been beaten by Morley. When Ken warns Tom that Morley plans to kill Palmer, Tom hurries into the hallway and watches as Palmer's dog attacks Morley on the staircase. Just then, Donovan arrives, a gunshot rings out and Palmer falls dead, shot by Tom in self-defense. Later at the airport, Bonnie tells Tom that she is leaving him to return to Texas. The dejected Tom then declares that he is foresaking all women until another damsel in distress begs him for help.