A man hires Diamond to watch over his frightened wife while he is out of town, but then Diamond is approached by a pair of doctors from a mental institution who claim she is an escaped patient.

Diamond plays a game of cat and mouse with an escaped convict who bears a grudge against Diamond for bringing him to justice.

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.

While briefly stopping in San Francisco, Diamond finds himself the target of a gunman.

Diamond is hired to verify the authenticity of an ancient Greek statue, which is suspected of being fake when it is offered for sale at a figure far below its true value.

Diamond uncovers a narcotics smuggling operation while investigating the murder of an art restorer who was killed in his workshop.

Diamond promises a dying gangster that he will take care of the gangster's girlfriend, unaware that the promise will endanger his life.

Diamond poses as a rich Canadian and infiltrates a gambling racket in order to learn the truth about a businessman's claims that he witnessed a murder.

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.

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.

An old nemesis of Diamond's on the police force has Diamond arrested on murder charges after the girlfriend of an escaped convict is found murdered.

Diamond unravels a story of unrequited love and revenge while tracking down a fugitive gangster who is in the possession of a valuable stolen necklace.

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.

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 finds himself in a deserted amusement park on the trail of a desperate fugitive murderer.

A woman in the hospital hires Diamond to trail her ex-husband, who she believes has obtained custody of their daughter to use as cover for his shady business practices.

Diamond finds himself facing off against the mob when is hired by a woman to prove that her fiancee is innocent of killing a man in a hit and run auto accident.

Diamond is hired to protect a lady politician whose supporters fear she may be kidnapped by the opposition.

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.

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.

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.