Mannix gets involved in a case of blackmail against a prospective governor... and learns that the blackmailer died years ago.

The daughter of a recently murdered ex-con hires Mannix to recover the missing money her father supposedly stole... and bring in the killers that are now after her.

A hobo asks Mannix to find out why people are trying to kill him.

Politician Adam Langer hires Mannix to investigate Langer's own background to make sure there's no blackmail material that can be used against him. However, the people that Mannix checks with are murdered one by one.

A woman hires Mannix to prove that she killed a witness she was having an affair with, although her brother is accused of the murder.

Mannix's ex-girlfriend Carol turns up dead on a beach, apparently the victim of an accidental drowning. However, the facts don't add up and Mannix figures that Carol was murdered.

Peggy goes undercover to try to get the goods on a narcotics dealer selling dope to school kids, but the crooks soon get wise to her and send a man to romance her and find out if she's working with the police.

Two elderly sisters ask Mannix to investigate a hit-and-run, and he discovers that the driver may have been involved in a murder.

While attending a boxing match, Mannix witnesses someone take a shot at one of the boxers... but soon realizes that the shot was meant for him.

A man disappears after apparently drowning the wife of an electronics company's head. The man hires Mannix to find the killer, but the PI soon discovers facts that suggest the accused killer is innocent.

A wealthy man hires Mannix to clear his wife of murder, but it turns out that the man--and many others--also wanted the playboy victim dead.

Mannix investigates a woman's murder, and uncovers evidence that the son of one of Peggy's friends may be responsible.

Mannix is jailed while investigating whether a young man's death was murder or accidental death... and two deputies plot to make sure the PI doesn't leave jail alive.

When a PI friend is murdered, Mannix investigates the four cases he referred to the man, figuring one of them led to the killing.

Mannx ends up in the middle of a feud between Armenian farm workers and a land owner who they claim cheated them .

Mannix is caught between an exiled mob boss and his successors, who think the PI is working for the man they hope to depose... permanently.

A young boy hires Mannix to investigate the theft of his stamp album... which may be more valuable than it appears.

Dan Turner claims that he's Alex Lachlan, an Army Ranger who was presumed dead in Vietnam and now has amnesia. His family has doubts that "Alex" is who he says he is, and hire Mannix to find out.

Mannix goes undercover to find an informant in a mobster's organization... and falls in love with the head mobster's girlfriend.

Mannix investigates the death of a war buddy who married into a wealthy family, and was killed by a hand grenade tossed into his elevator.

An industrialist's wife disappears off of their sailboat, and the industrialist hires Mannix to find her. But when Mannix finds her, the mystery truly begins.

Mannix is hired to find out who is threatening a surgeon's life.

A former penitent comes after a retired priest who he confessed a murder to, believing his secret is no longer safe.

A criminal who Mannix once helped capture kills a young officer who takes the bullet meant for the PI. The criminal, Victor Roarke, offers to take the police to the body of a missing judge, and things get more complicated from there.