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.
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
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
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).