An Irish terrorist uses disguise and deception in order to be able to smuggle explosives for the Troubles.

McGarrett engages in a personal struggle to clear the record of an officer and close friend accused of criminal activity.

When a Russian tennis star wants to defect, McGarrett must work to prevent an international incident.

A secret submarine, the murder of a Navy officer and strange amnesia create a puzzling case for Steve McGarrett.

An up-and-coming young politician is blackmailed in order to affect his leadership of an congressional investigation.

Five-O's world is shattered when mobsters catch Chin Ho undercover and order him to be killed.

When a preacher is attacked by a man convinced that he is responsible for his wife's death, Five-O investigate more closely and discover some less than godly motives.

Two rival mobs attempt to take control of the disco scene in Honolulu.

The rival gangs are on the brink of all out war, and Five-O must struggle to stop them.

When the son of one of Steve's friends dies of an overdose, he goes after a doctor that he suspects of over-prescribing drugs.

The hunt for a high-rise killer is made more difficult for Five-O when a journalist offers to share his profits in exchange for the killer's story.

McGarrett finds himself stymied when Hawaiian nationalists and local underworld mobsters clash over a union election.

Labouring under a ban on cooperation by native Hawaiians because of a Kahuna, McGarrett must try to prevent war on the streets...

When the husband of a policewoman is gunned down by opportunist robbers, she resolves to catch them any way she can.