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.

A group of high society men set out to see that justice is done - the catch being that it is justice on their terms only...

Jessica Humboldt, an astrologer and friend of Agnes DuBois, comes to McGarrett with news that a forthcoming match will be disastrous for a boxer. McGarrett must overcome his suspicions and crack the case.

Tony Alika and Guido Marioni, killer of Kimo's family, together hatch a plot to frame and embarrass the Five-O team by making them look stupid or corrupt.

When a woman is stalked by a strange figure, she seems to be seeing things and her friends are worried as to her mental health. However, events prove her case and an accomplice is revealed...

When two surfer bums use a gun to rob a shop, it starts off a trail of death and misery involving children, politics and blackmail.

A group of terrorists capture a female officer and use her to further their aims, and McGarrett and the team must find a way to take them out without endangering the life of Officer Dean.

A young man on vacation has strange visions that lead him to the site of an old murder and help him discover a lost family.

When two healthy young people die mysteriously, local traditions prevent post mortems, and a strange conspiracy is gradually uncovered when Truck seems to fall under the power of a Kahuna...

When a rich socialite is kidnapped, her husband insists that Five-O stay out of the case. However, his reasons may not all be on the level as events take a series of twists and turns...

McGarrett and Kimo must stop a gang of trained assassins from disrupting a meeting of energy ministers.

McGarrett is suspicious of an aide who arrives in Hawaii to retrieve millions of dollars held in trust for a Southern Asian state and he must prevent a daring gold robbery.

A gang of clever students use radio-controlled planes to execute the theft of Queen Liliokalani's jewels.

The murder of a Nazi-hunter and discovery of a World War II medal set McGarrett and the team on the trail of a Nazi war criminal living in Honolulu...

A group of seemingly harmless birdwatchers are the target of a vendetta. Five-O must discover why they were a target and stop any further violence.

A politician trying for the Senate is weakened by the murder of the man who is blackmailing him.

The series concludes with the final showdown between McGarrett and Wo Fat. Three scientists have gone missing. They have one thing in common: they all attended a symposium that discussed a possible space-based, laser defense system. McGarrett impersonates a fourth scientist, Dr. Elton Raintree, who attended the same gathering and is soon abducted. Wo Fat is behind it all and wants the scientists to complete their work and produce such a device.