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.

It's Christmas in Hawaii, but instead of celebrating, Five-0 is negotiating a hostage situation when the man who killed McGarrett's father resurfaces. The murderer, Victor Hesse, threatens to detonate an explosive that he's strapped to Chin Ho's chest.

When McGarrett is kidnapped by Wo Fat, he experiences what would have happened to the team if they had taken a very different path, on the 100th episode.

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.