Mannix is hired by former crime boss, Sam Dubrio, when his daughter is kidnapped. His plan is to set up a ransom and then pay off his pick up man to turn in his boss.
People begin to be killed off after Mannix is hired to drub up information which could hurt Adam Pierson from being elected governor.
When an old flame is found dead, Mannix is named the prime suspect.
When a secret formula disappears, Mannix is hired to find the chemist who worked on its creation.
Mannix is hired to help get the father of a young girl off death row, who was accused of a crime he didn't commit. Meanwhile, Joe romances the mistress of a wealthy industrialist her is investigating.
While investigating the location of a missing person, Joe uncovers the death of a colleague who appears to have committed suicide.
Mannix heads for a hippie retreat to investigate the disappearance of a missing girl who is linked to the death of a basketball star.
A mentally unstable woman is having trouble grasping the difference between a nightmare and reality. Mannix is hired to figure which of her companions is creating her confusion.
Mannix is stuck in a farm town with an injured foot and a group of citizens who seem to be keeping a deadly secret from him.
Mannix is on the middle of a fence when it comes to an intense child custody case, where he is working for the mother while seeing the father dash attempts on his life.
Mannix is hired to investigate when a psychiatrist is blackmailed after some of his files are lifted from his office.
A million dollar libel suit against a crusading publisher may be tied to the mob.
Mannix is hired to determine which cops are tied in with a vice ring.
Mannix investigates why a man who is against the evils of drink is spending a load of cash and time at a alcoholic retreat in Mexico.
As movie starlet, Anne Marion, is scheduled to release her tell-tale memoirs, an attempt is made on her life.
Mannix is hired when a sniper begins killing off citizens and the prime suspect is an escaped mental patient.
Intertect is accused of stealing plans and and a formula to create a laser ray, forcing Mannix and Lew Wickersham into a deadly feud.
Mannix is fired from Intertect while his boss suffers from a medically induced psychosis, causing Joe to use desperate measures to crack the case and save Wickersham's life.
Mannix' attempt to locate a stolen necklace leads him onto a case of murder and fraud.
Bernie Farmer is mistaken as being responsible for a missing million dollars, used as bait in a drug ring.
Mannix is hired to investigate an alleged miracle which is happening upon the land of a crime boss.
Mannix discovers a 20-year old crime is attached to a mysterious hit and run accident.
When Mannix is hired to prevent a murder of a mystery writer, the intended victim wants no help in solving the crime himself.
Mannix is hired to investigate a possible art forgery of a Renoir, when the collector sees the model who posed for the painting in person.