It is the first of three films starring Red Skelton as Wally "the Fox" Benton, who writes and acts in radio murder mysteries.

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 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.

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.