Steve McGarrett is summoned home to the island of Honolulu to bury his father after he is murdered by a madman. Governor Jameson wants Steve to head up a new elite police unit and she will give him full authority to get the job done. Initially he turns down the job, but when he meets the man in charge of the unit, he changes his mind.

With the help of an ex-HPD officer-turned private detective, Five-0 tries to solve the homicide of a woman who was working for a hula dancing company that is actually a front for an escort service.

Five-0 must find a kidnapped patient infected with a contagious and lethal strain of bird flu which the culprits intend to weaponize.

On the eve of Kono’s wedding to Adam, Five-0 must stop a fanatical patriot intent on starting a new war on terror by detonating stolen nuclear warheads and framing a terrorist leader.

While Five-0 investigates a scuba diver’s death from a gun recently used in another murder, McGarrett prepares to propose to Catherine.

Five-0 must work with charming con man Hank Weber to find a killer when his female partner is murdered on the job. Also, San Francisco Police Inspector Abby Dunn comes to O’ahu and works with Chin to investigate the murders of five Chinese arms dealers.

When Five-0’s sketchy confidential informant is accused of murder, McGarrett asks his old friend Odell Martin to defend him.

McGarrett investigates a cold case from the 1940s, one that his grandfather and the famous Honolulu detective Chang Apana worked on, and he tries to deduce how the case could have been solved. Also, McGarrett and Danny get ready for the opening of their restaurant.

A new ally helps McGarrett and Five-0 when mob bosses on the island are being targeted by an assassin. Also, Five-0 says goodbye to one of their own.

When a list of undercover CIA agents is stolen, Steve and Five-0 enlist the help of Magnum, Higgins, Rick and TC to get it back and protect national security. Also, Higgins gives Tani some personal advice.

The crossover continues on Magnum P.I. S02E12 Desperate Measures (II).

Soon after Danny meets the girl of his dreams, they get into a potentially fatal car accident in an area far from help. Also, McGarrett enlists Quinn and Tani to help when Eddie the dog suddenly shows signs of PTSD.

Danny is abducted and badly wounded by Wo Fat’s wife, who is after the cypher Steve’s mother left him. Steve works to solve the case his father left for him 10 years ago.