1
A amputee with no hands sets out to kill every police officer who contributed to his injury, and that includes Steve McGarrett.
2
Murders are being committed seemingly at random every six weeks, and McGarrett is at a loss to understand the motives for these crimes. However, a newspaper may hold the answer.
3
When a large amount of diseased rats are found on a boat with all the crew dead, Five-O must contend with an outbreak of bubonic plague.
4
A family of white-trash mass killers arrive on Hawaii after wreaking a trail of devastation on the mainland, and McGarrett must catch them before they can do more damage on the islands.
5
Buildings are being set on fire on Sundays, and a known firebug is the top suspect. However, McGarrett begins to think that others may be responsible.
6
A corrupt federal agent who is tracking a man under indictment for tax evasion kills him for the $600,000 he is carrying, and then loses the money.
7
The killing of an important pimp threatens an all out war between two competing vice empires.
8
A string of five murders of wealthy men leads McGarrett to a crooked inheritance scheme.
9
A glamorous woman sets up an opal smuggler so her accomplices can rob both the smuggler and a jewellery store at the same time.
10
A dictator must evade a female assassin sent to kill him, one that looks just like his own daughter.
11
McGarrett brings in a document expert to help him crack a case involving forged government securities, but he soon becomes suspicious of the expert as well.
12
A nuclear scientist becomes involved in an extortion plot when a gang threaten to explode a small nuclear weapon somewhere in Honolulu.
13
Harry Foxton, a gambler, is himself the subject of huge bets over what hour he will die. McGarrett must work out the gambler's complex relationships to get to the bottom of this case.
14
A thief known for using sleight-of-hand is hired to steal a valuable nickel, but the coin ends up on a journey across many miles and through many hands.
15
A mock military emergency leaves a bank open for a robbery, and Five-O must travel to the opposite side of Oahu to find out more in their investigation.
16
An exciting surf beach is the location for a filming session, where a man catches a killer on camera.
17
A pair of crooks team up with local criminals and use phony diamonds as bait to prey on wealthy male tourists. McGarrett and Five-O must shut off this sinister racket.
18
A young man witnesses a murder, and finds himself and his family are now the killer's targets.
19
The son of a Federal Narcotics officer becomes involved in a heroin refining operation.
20
When a man is found dead with gold dust on him, McGarrett and his team must investigate where the stolen gold came from and how it is being bought onto the market.
21
A series of rapes and murders occur, and the main suspect seems to be a police officer...
22
A right-wing crackpot, Cord McKenzie, metes out 'justice' to people who have been found innocent on technicalities or released early. He thinks he is helping the police, but McGarrett thinks otherwise.
23
While investigating a robbery and kidnapping, the trail of clues leads McGarrett and the team to an ocean liner with a deadly passenger.
24
An aging jewel thief steals from rooms at Waikiki hotels, and taunts Five-O by leaving a trail of clues behind.