Suffering from a fatal gunshot wound, Dr. Lloyd Craig struggles to Margot Shelby's apartment and shoots her before dying himself. While she is dying, Margot recounts for police detective Joe Portugal the events that led to her shooting: After Margot's boyfriend, Frankie Olins, hides the $400,000 he stole in a bank robbery, he is arrested. Because a guard was killed during the robbery, Olins is sentenced to die in the gas chamber. Margot pretends love for gangster Jim Vincent and promises to share the stolen money with him if he helps remove Olins' body from the gas chamber immediately after the execution. She then seduces Craig, the prison doctor, and persuades him to bring Olins back to life by administering an antidote for cyanide gas poisoning. When Olins is revived, he gives Margot half of a map showing the location of the stolen money and keeps the other half for himself. Later, encouraged by Margot, a jealous Vincent shoots Olins and takes his half of the map. Because his doctor's license plates will enable them to pass through the police roadblocks, Margot and Vincent force Craig to drive them to the hiding place. Vincent plans to kill Craig, but before he can do so, Margot, who wants all the money for herself, tricks him into fixing a flat tire and runs him over with the car. She then forces Craig to dig up the treasure, and after he does, shoots him. Having finished her story, Margot dies. Portugal then opens the box and finds only a single dollar bill inside, along with a note from Olins stating that he did not intend to leave any money to a double-crosser.