Air date - Tue 10th of September 1974
Danno and a college professor are kidnapped by a revolutionary group of young radicals led by a hardened criminal.
Air date - Tue 17th of September 1974
A geophysics expert, Bernard Brown, is heavily in debt, so he comes up with a plan to cause an explosion in the Hawaii Volcanoes National Park, which will cause lava to pour all down the hillside and into the city of Hilo, unless the Governor comes up with half a million dollars as a ransom.
Air date - Tue 24th of September 1974
Eddie Josephs is a paranoid schizophrenic who is carrying out murders based on old Five-O cases. McGarrett must follow his clues and catch him before more people die.
Air date - Tue 1st of October 1974
A sophisticated thief is selling his goods to legitimate businessmen, and Five-O must find a way of trapping him.
Air date - Tue 8th of October 1974
Senator Harlan Henderson suffers from multiple personalities, and one side of him wants to kill himself. However, he ends up blowing up his secretary, and McGarrett uses handwriting and a diagnosis from a psychiatrist to try to crack the case.
Air date - Tue 15th of October 1974
A criminal, Hobart, is robbing liquor stores using a policeman's former gun, but the officer wants it back as he used it to kill a bankrobber five years before and the body has been uncovered.
Air date - Tue 22nd of October 1974
When his son is beaten to death, a powerful cattle baron takes matters into his own hands, and McGarrett and Five-O must prevent the rule of law from breaking down.
Air date - Tue 29th of October 1974
A gangland execution investigation takes a turn for the peculiar when it is found that the victim had two identities.
Air date - Tue 12th of November 1974
Five-O must investigate why three infallible security systems are failing to prevent the theft of priceless artworks.
Air date - Tue 26th of November 1974
Air date - Tue 3rd of December 1974
Two conmen use a gang of Five-O lookalikes and doubles to extort money from Honolulu businessmen.
Air date - Tue 10th of December 1974
Wo Fat returns to Hawaii in order to have a Chinese diplomat whom he classes as a foolish peace-maker assassinated.
Air date - Tue 31st of December 1974
McGarrett and Five-O need to find out why a Japanese banker ritually killed himself and catch a true criminal into the bargain.
Air date - Tue 7th of January 1975
A Honolulu murder is mysteriously linked to a human fossil smuggled out of China in the Second World War.
Air date - Tue 14th of January 1975
An investigation into a murder is sent off track through the modification of computer information, and Five-O must use the latest technology to rescue the case.
Air date - Tue 21st of January 1975
Three women desperately in need of money take to armed robbery of tourist buses as a way to raise some quick cash.
Air date - Tue 28th of January 1975
When a young boy is arrested as a witness to a murder, McGarrett must contend with a fiery deputy public prosecutor.
Air date - Tue 4th of February 1975
A million dollar reward for the return of five figurines sparks off a trail of murder and theft that leads to Hawaii.
Air date - Tue 11th of February 1975
When a psychotic man kills his doctor, Five-O must use a unfinished painting to gather clues to his whereabouts.
Air date - Tue 18th of February 1975
An elaborate sea and air scheme for heroin smuggling goes unnoticed until one of the gang tries to sell out their plan for a fix of heroin.
Air date - Tue 25th of February 1975
McGarrett must prevent a mob war by tracking down an unknown hitman and his intended target.
Air date - Tue 11th of March 1975
When a deranged ex-Army officer shoots a policeman and takes a young girl hostage, McGarrett disagrees with a police captain over the best way to free her.
Air date - Tue 18th of March 1975
A Saturday Night Special passes from person to person and causes Five-O trouble and others misery.
Air date - Tue 25th of March 1975
Five-O works with a air traffic investigator in order to put a stop to illegal ticket sales which have already cost several lives.