A man hires Diamond to investigate an outer space society which he suspects is out to bilk his rich uncle since they have talked him into leaving the society $100,000 in his will.
Diamond is hired to protect a lady politician whose supporters fear she may be kidnapped by the opposition.
Diamond is hired to track down a gang of safe crackers and recover the money that they stole.
A man convicted of a jewel theft years earlier still claims to be innocent even though the jewels start to show up on the black market as soon as he is released from prison.
Diamond is hired to investigate a fire in a fur shop which killed an accountant who was working there.
A veteran journalist and a recovering alcoholic join forces in order to get a story on a protection racket.
Diamond uncovers a protection racket when he decides to learn why a pair of his Chinese friends unexpectedly call off their upcoming wedding.
A cowboy performing in a Madison Square garden rodeo comes to Diamond for help after he discovers his saddle strap cut and suspects that someone is trying to kill him.
While taking a break from an all night drive at a roadside cafe, Diamond meets a woman who gives him a look convincing him she is afraid of something.
Diamond is beaten and rendered unconscious by a man he suspects is an art thief. When he recovers he discovers that a beautiful woman has subdued his attacker.
Diamond is hired by a woman to clear her son of charges of murder, since he is a member of a gang which robbed a liquor store and killed the sales clerk.
A jewelry store owner comes to Diamond for help when one of his employees refuses to return gems he had been assigned to clean unless he is given a large cash stipend.
Diamond goes under cover as a truck driver in order to investigate a truck hijacking in which the driver was killed.
Diamond sets out to find the man who is trying to kill him and who failed in his last attempt, leaving an innocent bystander dead.
Diamond fails in his efforts to protect a shady night club owner who believes that someone is out to kill him.
While investigating the death of an investment counselor, Diamond learns that a letter has recently been stolen from the deceased's attorney.
Diamond is hired by a singer who finds himself being threatened by extortionists.
Diamond and his client are kidnapped by gangsters who threaten to kill both of them unless Diamond reveals the location of valuable paintings from another case.
Diamond is called upon to investigate the murder of a film producer and upon arriving at the scene of the crime learns that the police have not been notified of the man's death.
After a policeman friend of Diamond's is killed while on patrol, Diamond decides to do an investigation of his own to insure that the killer is brought to justice.
Diamond uncovers a narcotics smuggling operation while investigating the murder of an art restorer who was killed in his workshop.