Wally Benton (Red Skelton) is the star of a mystery series on radio, The Fox, which he writes himself, inventing for each episode a crime that has "only one loophole" so the criminal can be caught. He is about to elope with Carol Lambert (Ann Rutherford), but his agent (Eve Arden) tells him he must go out with the sponsor's daughter, Fran Post (Virginia Grey), or risk his show being canceled.
Outside the city, at a mansion called Silver Haven, Joseph Jones (Conrad Veidt) runs a cult that promises serenity and contact with the dead, but is really just a scam to collect donations. He learns that a member has died and bequeathed a life interest in $1,000,000 to her nephew Harvey Upshaw (Lloyd Corrigan), with the principal going to Silver Haven on Upshaw's death. Jones, angry that she did not leave the money directly to his cult, determines to have Upshaw killed at once, but he must avoid suspicion. Some of Jones's henchmen are fans of The Fox and admire Benton's plots, so he gets the idea to kidnap Benton and make him invent a real crime with no loopholes. Learning that two different women are expecting to meet Benton that night and one is his fiancée, he has Lambert and Post kidnapped as well.
Benton tries to protect the women, but is out of his depth. After a bumbling escape attempt through a secret passage fails, he decides he needs to come up with a plot as Jones demands. He has the idea to substitute poison for the tooth powder that Upshaw will undoubtedly take along as he flies overnight to meet his aunt's lawyer. The women are aghast at Benton's cooperation, but when the poison is brought to Benton, he puts it in a packet but then substitutes another harmless one. However, this gets lost and another packet is made up with real poison: Upshaw is in real danger. And so are Benton, Lambert, and Post, as Jones will have no reason to let them live once the plot succeeds.
Benton finds a hidden telephone, but before he can reach the police, he is seen and the phone is ripped from the wires. Jones leaves and Benton is locked in with the women in the same room. He touches the telephone wires together to simulate dialing 0, but cannot talk to the operator without a telephone. But, noticing a radio in the room, he uses his knowledge of radio to improvise a way to use it as a phone: the loudspeaker will double as a microphone if they swap the right wires back and forth each time he starts or finishes talking.
He reaches the telephone operator and tries to get a message sent to Upshaw's flight, but Jones's man on the flight finds a way to disable the aircraft radio, and contact is lost. Benton then has the operator contact his radio station, where it is almost time for The Fox. They patch his phone call through to the transmitter and he begins telling all his listeners what has been happening.
But they have to speak loudly, and the one dim-witted guard who was left outside the door bursts in. They save themselves by convincing him they are just passing the time by pretending to do a radio show. He finds the idea fun and even participates, adding useful information such as the mansion's address. Unfortunately, the local police assume it is fiction, like the recent War of the Worlds broadcast, so the three hostages are not saved until Benton's friends from the radio station arrive with city police.
Meanwhile, on the flight, Upshaw learns of the plot thanks to a small boy who enjoys The Fox and listens to it by an ordinary radio on board. Warned not to brush his teeth, he remarks, "I won't even take them out".Red Skelton as Wally Benton
Conrad Veidt as Joseph Jones
Ann Rutherford as Carol Lambert
Virginia Grey as "Fran" Post
Rags Ragland as Sylvester (as "Rags" Ragland)
Henry O'Neill as Philip Post
Eve Arden as "Buzz" Baker
Paul Stanton as Jennings
Don Douglas as Gordon Thomas
Don Costello as "Noose" Green
William Tannen as Robert Graves
Reed Hadley as Beau Smith
Mariska Aldrich as Hilda
Lloyd Corrigan as Harvey Upshaw
George M. Carleton as Deputy Commissioner O'Neill (as George Carleton)
Will Lee as Herman
Ruth Robinson as Mrs. Robinson