Writer Jan Cornell is broadcasting her weekly radio show, This Crime Was Never Solved , in which she dramatizes unsolved murder mysteries, when she makes an unscripted announcement that on her next show, she will solve the ten-year-old murder of actress Lenore Fenwick. Jan's producer, Don Fletcher, is horrified by her assertion, but her sponsor, cigarette manufacturer A. J. Stanley, encourages her. Jan reveals that she wants to solve crimes rather than merely report them because of a newspaper item stating that she is losing her audience to Michael Jerome, a rival radio detective. While Jan's pal Smitty is excited by the show's new direction, actress Mida Kent becomes uneasy and later that night, calls Jan and asks her to come to her apartment, where she will reveal information about Lenore. On the way, Jan's friend, New York Chronicle columnist Bill Burton, introduces her to Mike, who tags along with Jan and Smitty despite Jan's dislike of him. At the apartment, they find Mida's body, and while waiting for the police, notice that a photograph has been removed from a prominently displayed frame. Although Jan feels responsible for Mida's death, she is determined to continue the Fenwick investigation and goes with Mike to the Chronicle 's library, which is presided over by the strange Mr. Crunch. By examining back issues of the newspaper, Jan learns that Mida and Lenore had started out in burlesque together, and that Mida and Lenore's secretary, Irene Hill, were present at Lenore's lodge on the night of the murder. An item about Lenore's mysterious first husband also makes Jan suspect that he might be the killer. The next evening, Jan and Smitty are followed by Mike when they go to Lenore's lodge to record sound effects for the broadcast. At the lodge, a veiled woman threatens them with a gun and orders them to stop their snooping, but she is shot and killed by an unseen assailant. Jan deduces that the woman, who is A. J.'s wife Eve, is actually Irene Hill, and A. J. bitterly affirms that he does not know anything of her past prior to their five-year marriage. When Jan questions pianist Ricky Moreno, Eve's paramour, he tells her that Eve stole a large sum of money from the lodge the night Lenore was killed, and that Mida had been blackmailing her for her share of it. Later, Jan receives a call from Crunch, who tells her where to find the photograph that was stolen from Mida's apartment. Upon retrieving the photograph, which is of Mida, Lenore and Lenore's first husband, Jan realizes that she has solved the case. During her broadcast, Jan reveals that Lenore concocted a swindle that was perpetrated by her first husband, who was sent to prison for it. When he was released, he murdered her, and has since murdered Mida and Eve to prevent them from talking. As the audience anxiously waits for Jan to reveal the killer, Bill tries to poison her, but his attempt fails and Mike gives Jan a big kiss after Bill is named as the murderer.