Leopold Kroner (Fritz Leiber, Sr.), formerly of Colby Enterprises, is released after five years in prison for embezzlement. Andrew Colby (Price), claiming that Kroner has threatened him, hires lawyer Bob Regan (Edmond O'Brien) as a personal bodyguard. That evening, Regan hears a gunshot from Colby's study and finds Kroner there, apparently trying to kill Colby. Regan kills Kroner when he turns around, pointing the gun at him.
Regan believes Colby's explanation that Kroner had become delusional and threatening, until Regan's police buddy Damico (William Bendix) lets on that he's suspicious that Regan murdered Kroner. Kroner's daughter shows up at Regan's apartment and tries, but fails, to murder him. She reveals that Colby had invited Kroner to the house that night and Kroner was of sound mind. Regan investigates further, getting information about Kroner's embezzlement case from a reporter and Colby's secretary, Noel (Ella Raines). Regan has a friend impersonate one of Colby's associates on the phone to deceive him into providing information about the embezzlement, unknowing that this associate is already long dead.
Colby uses this situation to his advantage to set a trap for Regan and Noel (whom he has decided has betrayed him). He innocently asks Noel to remove money from his safe, then after she leaves, he kills his associate Charles (John Abbott) with a weapon having Regan's fingerprints. The two of them are framed for theft and murder, but Lt. Damico tricks Colby into thinking Charles is still alive. Since Charles would reveal all of Colby's actions, that night Colby tries to sneak down and strangle Charles, only to be caught red-handed.