Air date - Wed 24th of September 1969
An army sergeant and a office worker have a scam in which they use bar girls to claim G.I. widow benefits, and then murder them to take the cash. McGarrett and company must use the girls to get to the core of the plot.
Air date - Wed 1st of October 1969
A Japanese World War II veteran, Yoshio Nagata, escapes from a mental hospital and tries to carry out his wartime orders to blow up a refinery.
Air date - Wed 8th of October 1969
A tsunami warning is called and a geneticist is evacuated from a conference. He is then kidnapped under the orders of Wo Fat, but he uses his diabetic medical condition as a ploy to stop Wo Fat from carrying out the plan to return him to China.
Air date - Wed 15th of October 1969
A middle-aged mainland hardware salesman uses a prostitute, and then witnesses her murder by a mobster. He refuses to testify because of the damage to his reputation and that he doesn't want to be involved. McGarrett must persuade him to do the right thing.
Air date - Wed 22nd of October 1969
McGarrett must interrupt his Sunday to deal with both terrorists and politics when a revolutionary group steal guns from a barracks for their overseas cause.
Air date - Wed 29th of October 1969
A university professor, Dr. Paul Farrar, is using hypnosis to programme students into becoming assassins. McGarrett uses a policewoman as bait for Dr. Farrar, but the plan goes wrong and her life is put in danger.
Air date - Wed 5th of November 1969
McGarrett must counter a threat by international terrorist Erich Stoss to use a fungus to wipe out Hawaii's sugar cane, half of the world's supply.
Air date - Wed 12th of November 1969
Four university students hatch a plot to steal the robes of King Kamehameha, and McGarrett and the team must apply pressure to the gang's weak point to retrieve the robes and catch the thieves.
Air date - Wed 19th of November 1969
McGarrett gets a phone call from Singapore and goes to rescue Nicole Wylie, a witness who has changed her mind and wants to testify. However, the pair must face many dangers on their return trip back to Hawaii.
Air date - Wed 26th of November 1969
An assassination attempt on a prominent politician, Charles Irwin, leads Five-O to Mike Finney, a former racketeer who has been clean for nine years. However, Finney insists he is innocent, and the trail of clues leads right back to Irwin.
Air date - Wed 3rd of December 1969
When a dictator's plane is diverted to Hawaii as part of a plan to kill him, McGarrett must deal with the complex politics of the situation and protect the hated leader.
Air date - Wed 10th of December 1969
When a young son of a businessman escapes from captivity by 'The Devil' and 'Mr. Frog', Five-O must recover the $300,000 ransom money that the desperate father paid.
Air date - Wed 17th of December 1969
Two young men play an increasingly dangerous and deadly game for the attentions of a beautiful but spoiled heiress, who plays them off against each other.
Air date - Wed 24th of December 1969
A career criminal, Connors, fools McGarrett and the team into protecting the wrong bank, and robs a nearby one, taking the wife of the manager hostage. Things turn ugly when one of his goons assaults and murders her. McGarrett must race to capture Connors before he can do any more damage.
Air date - Wed 31st of December 1969
McGarrett gets a surprise birthday party, but when he goes to pack the presents in his car, it explodes and blinds him. Danno, Chin Ho and Kono must work to catch those responsible, whilst McGarrett has to get used to not having his eyesight.
Air date - Wed 7th of January 1970
Air date - Wed 14th of January 1970
Two military policeman spot John Mala, a man who McGarrett has helped in the past, but who has gone AWOL. One of the policemen is shot, and tensions rise as Five-O and the army police clash in their techniques of investigation and their treatment of the local population.
Air date - Wed 21st of January 1970
A psychiatric worker, George Loomis, is trying to drive a fellow Vietnam veteran Ted Frazer crazy in order to cover up the fact that he massacred his own platoon during an action. Loomis kidnaps boys and drugs Frazer to make it look like Frazer is mad and to blame for the tragedy. McGarrett and the team must unravel this web of lies and clear Frazer.
Air date - Wed 28th of January 1970
Peter Corman is murdered during a game of poker, and his brother Lorenzo arrives in Hawaii for revenge. McGarrett must work out what happened and prevent Lorenzo from carrying out his intentions.
Air date - Wed 4th of February 1970
Chin Ho is accused of bribery, and cannot provide alibis for the nights in question. Worse, he is called to the middle of nowhere for a set-up. Chin's position is threatened, and the Governor orders an inquiry. McGarrett and the others must work out how Chin was framed and clear him of the accusations.
Air date - Wed 11th of February 1970
Lew Morgan and his wife are friends of Danno, but she is murdered, and Morgan sets out to find the culprit. However, his wife seems to be hiding secrets that may have caused her death.
Air date - Wed 18th of February 1970
A research scientist, Dr. Royce, is set up by revolutionaries to be transported away from the islands in a submarine. McGarrett must stop this from happening and also has to contend with the interference of federal agents in the case.
Air date - Wed 25th of February 1970
Dr. Alexander Kline, a biological scientist, views his work as evil, and to prove it, he plans to unleash a deadly germ that would kill thousands. Three dead cows lead McGarrett on a desperate chase to track down the toxin, involving a friendly telephone operator and top Washington agents.
Air date - Wed 4th of March 1970
Dr. Kline's deadly toxin is lost, he is having second thoughts about his plan, and McGarrett has to find the vial before it disintegrates and poisons the whole island. Already the toxin is doing its deadly work as innocent people come into contact with it.
Air date - Wed 11th of March 1970
Camilla Carver, a con-artist, blackmails a politician to take her to an event where she can steal the priceless Queen of Polynesia emerald and swap it for a fake. However, McGarrett and the team are at the event and make sure that neither the gem, Carver or her accomplice vanish.