An Irish terrorist (Stephen Boyd) poses as a priest in order to buy bombs and weapons in Hawaii for use in his home country.

McGarrett teams with a Navy commander (Mark Lenard) to search for a cargo ship hijacked by armed and dangerous men.

When a magazine reporter (Jean Simmons) writes a story about Five-O, McGarrett tries to discreetly locate two missing children.(A comic relief episode in which McGarrett finally gets the last word because the nosy reporter has been gagged by the kidnappers!)

Rookie cop Joey Kalima (John Rubinstein) is framed for departmental corruption by a group attempting to rob a bank.

A mysterious intruder kills two members of an archaeological dig that is attempting to find a king's burial site.

A recovering alcoholic ex-cop (Gil Gerard) puts his life in danger after he returns to Hawaii to make amends to McGarrett.

A Soviet tennis star is caught up in a murder after she decides to defect to be with her American boyfriend (Tim Matheson).

A Soviet spy ring led by a femme fatale (Maud Adams) kidnaps an engineer on a nuclear sub and steals classified data.

After an Asian diplomat drowns in a pool, his wife is convinced forces from their home country are responsible. Sian Barbara Allen guest stars.

The Governor asks a reluctant McGarrett to investigate the kidnapping of a racist shipping-magnate's daughter.

A physician is shot to death on a remote island and a young doctor from a local clinic is the prime suspect.

McGarrett must leave to handle family business during the investigation of a union candidate's murder.

A Congressman (David Birney) cheats on his wife while judging a beauty contest, and is blackmailed by a dangerous man (Soon-Tek Oh).

McGarrett teams with an FBI agent (George Grizzard) after the syndicate sends a hit man to kill an organized-crime informant.

After one of Five-O's undercover men is shot in the back, McGarrett enlists a Maui policewoman's (Carol Lynley) help.

A young man seeks revenge on a Hawaiian manufacturer who once tortured his father in a Japanese prison camp.

The heirs to a wealthy murdered artist are now falling victim to lethal booby traps set in their prized possessions ala Ten Little Indians

Five-O is summoned after a mystery writer (Mildred Natwick) investigates a fraudulent, and murderous, cryogenics outfit.

After the owner of a horse farm's body is found burning in a cane field, his widow becomes a prime suspect.

Guest stars: Andrew Prine and John Hillerman (the only one of the subsequent stars of Magnum, P.I. to appear on this series).