September 10, 1974 8:00 pm
Danno and a college professor are kidnapped by a revolutionary group of young radicals led by a hardened criminal.
September 17, 1974 8:00 pm
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.
September 24, 1974 8:00 pm
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.
October 1, 1974 8:00 pm
A sophisticated thief is selling his goods to legitimate businessmen, and Five-O must find a way of trapping him.
October 8, 1974 8:00 pm
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.
October 15, 1974 8:00 pm
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.
October 22, 1974 8:00 pm
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.
October 29, 1974 8:00 pm
A gangland execution investigation takes a turn for the peculiar when it is found that the victim had two identities.
November 12, 1974 8:00 pm
Five-O must investigate why three infallible security systems are failing to prevent the theft of priceless artworks.
November 26, 1974 8:00 pm
After an attempt is made on Steve McGarrett's life, he is drawn towards a female art dealer, but she too may not be good for his healthâ€¦
December 3, 1974 8:00 pm
Two conmen use a gang of Five-O lookalikes and doubles to extort money from Honolulu businessmen.
December 10, 1974 8:00 pm
Wo Fat returns to Hawaii in order to have a Chinese diplomat whom he classes as a foolish peace-maker assassinated.
December 31, 1974 8:00 pm
McGarrett and Five-O need to find out why a Japanese banker ritually killed himself and catch a true criminal into the bargain.
January 7, 1975 8:00 pm
A Honolulu murder is mysteriously linked to a human fossil smuggled out of China in the Second World War.
January 14, 1975 8:00 pm
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.
January 21, 1975 8:00 pm
Three women desperately in need of money take to armed robbery of tourist buses as a way to raise some quick cash.
January 28, 1975 8:00 pm
When a young boy is arrested as a witness to a murder, McGarrett must contend with a fiery deputy public prosecutor.
February 4, 1975 8:00 pm
A million dollar reward for the return of five figurines sparks off a trail of murder and theft that leads to Hawaii.
February 11, 1975 8:00 pm
When a psychotic man kills his doctor, Five-O must use a unfinished painting to gather clues to his whereabouts.
February 18, 1975 8:00 pm
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.
February 25, 1975 8:00 pm
McGarrett must prevent a mob war by tracking down an unknown hitman and his intended target.
March 11, 1975 8:00 pm
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.
March 18, 1975 8:00 pm
A Saturday Night Special passes from person to person and causes Five-O trouble and others misery.
March 25, 1975 8:00 pm
Five-O works with a air traffic investigator in order to put a stop to illegal ticket sales which have already cost several lives.