Upon the murder of psychiatrist Dr. Elton Parkson in his office late one evening, the police, Lt. Pat McKay leading the investigation, brings in police psychiatrist Dr. Everett Colner as an on-hands consultant as certain evidence indicates that there was some deep seated psychiatric issue in the perpetrator that was at the core of the murder. Those issues are that Dr. Parkson's desk drawers were laid out in a straight row in the center of the office floor, they otherwise undisturbed, and that Dr. Parkson himself, while strangled to death, was discovered locked in his office closet. Dr. Colner, who believes the perpetrator is one of Dr. Parkson's patients, is assisted by Dr. Parkson's nurse, Jean Smith, as they go through Dr. Parkson's patient files for any clues. Having narrowed down the suspects to six, Dr. Colner convenes those six together for a short experiment to try and discover more facts of any of those six tied to the murder. The doctor's methods are not as straightforward as Lt. McKay is led to believe, with the results equally as oblique as Dr. Colner tries to delve into the mind of someone who seems compelled to kill for the sake of killing.