When a letter bomb kills a Naval Officer whilst McGarrett is on Navy Duty, he is called upon to investigate and uncovers a plot involving an old nemesis

McGarrett must try his utmost to foil Wo Fat's plans which include hostages and brainwashing

McGarrett must again face mobster Charlie Bombay when a plane carrying them to Honolulu crashes in the forests

A British agent, Harry Wells, arrives in Hawaii in pursuit of a turncoat, but not all is what it seems for Five-O

Five-O must find a female courier who witnessed a murder before a hitman can

A road accident starts the trail towards a plot to use SAM missiles to bring down a VIP jet plane

McGarrett offers himself as a hostage exchange, but is then put on 'trial' by Honore Vashon

McGarrett meets his match in Dr. Grant Ormsbee, a grumpy and aggravating scientist who is sheltering a suspected Chinese defector

When a singer witnesses a murder committed by a racketeer, Five-O has to protect her until she can give evidence, but this is not an easy job

Danno's Aunt Clara becomes acquainted with a man on the plane to Honolulu, but becomes concerned about him afterwards. Dan, Steve and the others ignore her at first, but then the man turns up dead

A vice-principal enlists the help of his students and a submarine to smuggle drugs

When Five-O fail to prevent a series of thefts at dockside warehouses, an influential owner creates trouble for McGarrett

A writer who specialises in solving mysteries uncovers the body in a seven year old case, but it raises more questions than it answers

Three boys commit a gang rape on a waitress, but one is the son of a Senator and the crime is covered up

Whilst trying to stop the smuggling of small Oriental animal statues, McGarrett is caught illegally in possession of one of them as part of his personal collection

A disturbed young man steals nerve gas to use against a visiting royal family as revenge for the death of his father

When an elderly importer who was a World War II Japanese spy is killed, Five-O seeks his killer

A clear cut murder case against an island mobster is derailed due to McGarrett

A crooked contractor and a buildings inspector are under suspicion after the new Global Trade Center in Honolulu goes up in flames

When an airline stewardess and a hang-gliding instructor are murdered, Five-O must find the killers

Criminals threaten to use a special type of moth to wipe out the sugar cane on Hawaii and destroy the industry

The son of a Japanese businessman is kidnapped and held in a capsule underwater until a $1.5 million dollar ransom is paid

Ben Tanaka, a well-known ecologist, seems to be behind the kidnapping of a wealthy land developer's wife, but all is not as it seems and a conspiracy gradually reveals itself

McGarrett sends an undercover agent into a rehabilitation home for juvenile offenders to find out who is behind the theft of gold from dental supply warehouses