Rick and A.J.'s good friend, the coroner, asks the brothers to deliver a new video game to Las Vegas and they don't understand just how valuable it is until thieves attack.
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.moreless
A psychotic man named Ralston is killing the wives of members of his army unit, and Five-O, including Kono on his last case, must stop him before he commits any more crazed attacks.moreless
Three real estate crooks die horrible and mysterious shellfish related deaths, and McGarrett and the others must establish the link between them, and who has reason to want them dead.
An eccentric billionaire is accused of murdering a business associate, but will not leave his boat to defend himself against the accusations, allowing his associates to declare him mentally incompetent.
McGarrett and the team must find out who is behind a series of ecological stunts, when it is feared that a company executive will be their next target.
Five seemingly good citizens with different motives band together to steal $6,000,000 while McGarrett is away on the "Big Island" of Hawaii at a trial.
"Hippie freak" Ryan Moore robs an embezzler of the key to a locker containing $250,000. Danno tries to locate the girlfriend, the daughter of Moore's landlady when he was studying at Berkeley.
Danno's past comes back to haunt him when the vengeful brother of a young boy he shot is released from prison. The brother takes Chin Ho, Jenny and others hostage in McGarrett's office and threatens to blow them up. Danno must resolve the tense situation.moreless
When Harry Kellem hears a dying man confess to the murder for which Kellem was convicted, he takes a doctor hostage. McGarrett acts as negotiator in the tense situation.
McGarrett must apprehend two criminals who are on the run with the proceeds of a six-year-old kidnapping and murder. The criminals are also pursued by their former partners in crime.
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.moreless
Police officer Lew Morgan and his wife are long-time friends of Danno. When she is murdered, Morgan sets out to find the culprit. He uncovers secrets that may have led to her death, putting a strain on his friendship with Danno.moreless
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.
McGarrett refuses to accept that AWOL sailor John Mala shot a Navy MP without cause. Christopher Walken guest stars as the friend of the shooting victim.
McGarrett is blinded in a car bomb explosion. As the Five-O team searches for the would-be assassin, McGarrett tries to recuperate with the help of a tough nurse, Edith Lavallo (played by Marion Ross of "Happy Days" fame).