The series concludes with the final showdown between McGarrett and Wo Fat. Three scientists who have disappeared have one thing in common, they all attended a symposium on possible space-based, laser defense systems. 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.

Paul Burke guest stars as attorney David Lawrence, a political candidate whose promising bid for the U.S. Senate is endangered by the murder of a man who tried to blackmail him. Although Lawrence swears he knows nothing about the murder, he admits that the dead would-be extortionist did have knowledge about him that could have destroyed his political future.

During a stop off on a bird-watching expedition, tourists photograph an old sugar mill. They don't know that the mill is a front for a gold-smuggling operation and that one of their photographs has caught the leader through a window. The leader sends a pack of goons to kill everyone in the tourist party and steal their film. McGarrett and a newspaper journalist, who got hold of the pictures, must try to identify the man in the picture and take down his operation before he gets them.

Israel's celebrated Nazi-hunter Yuri Bloch has apparently been killed in Honolulu while trying to gather information about a war criminal named Emil Klaus. Knowing the Bloch would only have come to Hawaii if a former Nazi were hiding there, McGarrett and Five-O conduct their own search for Klaus -- while Bloch's partner lies badly wounded in a safe house, and the woman caring for him does what she can to assist while undercover.

Using radio-controlled model airplanes, three college students engineer the theft of the Hawaiian crown jewels.

The next-to-last show to be filmed features an escaped convict posing as a diplomat from a Far Eastern country in order to get at the country's store of gold bullion in a Honolulu bank. He hires experts with lasers to penetrate the light-beam screen surrounding the bank vault, burn a hole in the vault's floor, heat the gold until it liquefies and drain it through ceramic tubing. McGarrett gets a clue to what's happening when the bank's thermometer (located near the vault) starts to freak out, but he still has to find the thugs' hideout before they solidify the gold and escape.

A school for wayward girls, run by a friend of Steve McGarrett's, needs $15,000 for overdue taxes or the school will be closed. Former counterfeiter Willie McFee, a flower breeder who also is a general handyman and gardener for the school, decides to make one last print run with a set of near-perfect $20 plates he once crafted - but a mainland crime boss gets word that Willie's plates have surfaced, meaning that he can try to steal them for himself.

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

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...

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...

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.

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.

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.

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...

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.

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.

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...

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

The Hawaiian kumu mob attempts to take over a resort-workers union, to the fury of native Hawaiians who vengefully infiltrate and smash underground activities in lawless fashion. Meanwhile, Boston ex-cop James Carew trails a mainland gangster - who is providing aid and comfort to the kumu - to Hawaii in order to get information on the murders of his wife and child.

The Hawaiian kumu mob attempts to take over a resort-workers union, to the fury of native Hawaiians who vengefully infiltrate and smash underground activities in lawless fashion. Meanwhile, Boston ex-cop James Carew trails a mainland gangster - who is providing aid and comfort to the kumu - to Hawaii in order to get information on the murders of his wife and child.