Victor Reese and his wife Nora are conning rich widows out of their savings, and then poisoning them and dumping them in the ocean. McGarrett and company hatch a plan to use a female officer to trap the duo.

A young singer, Bobby George, plans his own kidnapping as a stunt, but when his father offers $500,000 for his release, his co-conspirators decide to double-cross him and take the money.

When a young female student is found murdered on campus, suspicions fall on her boyfriend but McGarrett senses that something is not right.

A man is found dead after having been robbed by a motorcyclist with a gun, and McGarrett is shocked to discover that the man was suffering from bubonic plague. The islands are quarantined, and the team must follow a series of clues to discover the cause of the outbreak.

When the boxing son of a policeman, Phil Kalama, is killed, he starts a personal vendetta, and McGarrett must both solve the crime and stop Kalama from committing another murder.

McGarrett must counter a threat by international terrorist Erich Stoss to use a fungus to wipe out Hawaii's sugar cane, half of the world's supply.

An assassination attempt on a prominent politician, Charles Irwin, leads Five-O to Mike Finney, a former racketeer who has been clean for nine years. However, Finney insists he is innocent, and the trail of clues leads right back to Irwin.

McGarrett agrees to let Toni, a tough female convict, get married and have a honeymoon in protective custody as long as she will testify against a local hood.

A crazed electronics wizard threatens the lives of a psychiatrist and his patients by using electronic devices and gadgets.

An exciting surf beach is the location for a filming session, where a man catches a killer on camera.

Five-O become involved in a complex case of body-switching, mystery investments and suitcases full of money.