Filmed entirely on location in Hawaii, the show followed Jack Lord as he played Steve McGarrett, head of an elite state police unit investigating "organized crime, murder, assassination attempts, foreign agents, felonies of every type." James MacArthur played his second-in-command Danny ("Danno") Williams, with local actors Kam Fong, Zulu, Al Harrington, and Herman Wedemeyer, among others, playing members of the Five-O team. Guest stars included Helen Hayes, Ricardo Montalban, Leslie Nielsen, Herbert Lom, Hume Cronyn among others. McGarrett's nemesis is the evil Wo Fat - "a Red Chinese agent in charge of the entire Pacific Asiatic theatre.