James Parkerson is a psychology professor who places an ad in the newspaper offering advice on how to murder one's spouse. He gets a response from the police, but manages to convince them that he is merely gathering research for an experiment. Later, he is contacted by a man named Robert Johnson who is searching for a way to kill his lover's husband. From Johnson's description of his lover and her husband, Parkerson realizes that Johnson is talking about his wife Doris and himself. Johnson is planning to kill him, but doesn't seem to realize that his target and the man on the phone are one and the same. Parkerson hires a hit man named Bingham to kill Johnson. Unfortunately, Johnson kills the hit man. Johnson realizes that Parkerson knows about him so he contacts Doris. He tells her that they should kill Parkerson and then make it look like the hit man did it. Unfortunately, Doris still loves her husband and has no plans to kill him. She only began her affair because of her husband's lack of attention. She manages to take the gun from Johnson and calls the police.