The feature-length pilot episode for Hawaii Five-O aired on September 20, 1968, and the series premiered the following week, launched to a roaring start with what seemed -- especially at the time -- like a first-rate thriller, which incorporated elements of espionage and topical political concerns within a police procedural, all in a colorful, exotic setting, with a mostly charismatic cast. There was even something of a nod to the more outre side of feature films of the era in the casting of Khigh Diegh as Wo Fat, the Chinese agent using sensory deprivation as a means of breaking and brainwashing American agents -- Diegh had made his big-screen debut in 1962, in a somewhat similar role, in John Frankenheimer's The Manchurian Candidate, a fact that wouldn't have been lost on serious spy-thriller enthusiasts; and, indeed, he was so good here, that Wo Fat became a recurring villain across the run of the series. Most of the cast of the subsequent series was in place for this vehicle as well -- beyond granite-jawed Jack Lord as Steve McGarrett, this included Zulu as Kono Kalakaua (usually referred to simply as "Kono") and Kam Fong -- a retired Honolulu police officer in real life -- as Chin Ho Kelly. The exceptions were Tim O'Kelly, who was apparently a little too bland as Danny Williams, the right-hand man to McGarrett, and was replaced in the actual series run by James MacArthur; and Lew Ayres, who was replaced in the role of the governor of Hawaii by Richard Denning. Otherwise, on its own terms, the action here is fast and furious, and was quite riveting in 1968, even if elements of it seem dated today -- Nancy Kwan's college student, with her suspicion of police officers, is straight out of 1968 stereotypes about college students; and, of course, the spectre of the Vietnam War, at its height in 1968, is never far from the plot's focus on efforts to destroy America's counter-intelligence network in the Far East.
As with most other series pilots of the period, this episode -- retitled "Cocoon" (a reference to a vital clue) in syndication -- is a kind of idealized and, if you will, slightly dishonest presentation of the program it is meant to sell. For starters, in a regular installment of a weekly series, the producers would only have 50 minutes of screen time, not 105 minutes, in which to tell their story. Additionally, for a regular series episode, they could never have afforded the services of Leslie Neilsen (even the "old," pre-comedy star Leslie Neilsen), Andrew Duggan, James Gregory, Khigh Dhiegh, and Lew Ayres, or the elaborate sets and settings used here. And to be sure, the producers and the network got a lot of mileage out of this episode, re-running it nationally several times across the run of the series.