Private detective Bill Reardon has made little progress in his investigation of a series of robberies at the Nacelle jewelry store, which is owned by Francine Nacelle and her husband, along with their partner, Rolfe Davis. Bill suspects that Clarence Crenshaw is the culprit and, unknown to Bill, his wife Sally, also a private detective, has taken Crenshaw on as her own client. When Sally telephones Crenshaw to meet her at a beauty parlor, he is captured by the police. Later, the Reardons meet the Nacelles and Davis at a nightclub, where Davis intercepts a note meant for mobster Tony Croy. In the note, he finds a key with instructions to a file cabinet in the jewelry store. When Davis goes to the store to open the drawer, Croy watches as he is shot by a rigged gun in the drawer. Hoping to deflect suspicion away from the imprisoned Crenshaw, Sally steals a necklace from the store, but her plan fails when Flannigan, Bill's operative, finds Sally's broken heel at the scene of the crime. Suspicion is soon cast on Croy, in whose apartment Sally finds a cigarette case belonging to Francine. Croy turns out to be Francine's first husband, whom she never bothered to divorce. When Croy tries to blackmail Francine, she directs him to a safe that has also been rigged with a gun. When Croy opens the safe, the gun fires and he is killed. Mr. Nacelle finds the body, and when police arrive, Francine pretends to suspect her husband of the murder. When Bill discovers how Davis was killed, Crenshaw reveals that he was in league with Francine, with Croy serving as their fence. Crenshaw also confesses that Francine is planning to kill Sally in the same manner as she did Croy. Bill rushes to the store and arrives just in time to prevent Sally from being killed. Bill attempts to trap Francine into an admission of guilt by having Sally play dead, but she overhears their plan and flees. With the help of Flannigan, however, Francine is captured and turned over to the police.