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.
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.
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.
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.
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.
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.
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.
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.
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.