The Enterprise travels to Beta III to learn what happened to the U.S.S. Archon, which went missing a century earlier. A crewman in the landing party disappears, while another (Sulu) returns in a strange state. The word “Archon” was the title of certain Greek heads of state, incl. those in the Athenian Republic. It comes from Greek root “arch”, meaning “leader, highest, chief” (found in monarch, hierarchy, and anarchy).
Kirk beams down w/ another landing party just before the chaos of “Festival” (or “Red Hour”) begins at 6PM. They say they’re visitors from “The Valley,” escape the streets for a hotel, where the owner (Reger) and town elders ask if they are “Archons.” To learn more, Kirk has to convince some citizens to disobey Landru (who has ruled this society for 6,000 years). There are Lawgivers (wearing brown robes w/ long staffs in hand) everywhere; they are watching and waiting for those who disobey.
Spock: This is a soulless society, Captain. It has no spirit, no spark. All is indeed peace and tranquility – the peace of the factory, the tranquility of the machine, all parts working in unison.
Kirk: Mr. Spock, the plug must be pulled.
Kirk: Landru must die.
Spock: Captain, our prime directive of non-interference…
Kirk: That refers to a living, growing culture. You think this one is?
This ep contains the first mention of the Prime Directive. This is also the first ep where Kirk, Spock, McCoy, and their landing party are disguised in the clothes of the native society. Nimoy looks a but more elegant than usual w/ a black cape (to cover up Spock’s Vulcan ears). Spock is seen sleeping with his eyes opens- another element of the alien side of his character. In the dungeon, Spock punches a guard in the face w/ his fist (first time we see) instead of using the Vulcan neck pinch.
This story is the inspiration for The Purge (2013) and its sequels; I haven’t seen those movies yet. Ben Stiller named his production company Red Hour; he is a huge fan of ST: TOS. The location scenes were filmed at the 40 Acres backlot in Culver City, CA. This is the same place where Miri and The City on the Edge of Forever were shot. The sets were featured prominently on The Andy Griffith Show and originally constructed to portray 19th century Atlanta for Gone with the Wind (1939). Westerns were very big in the ’60s, so it was cost-effective to use the sets, as well as the costumes.
 Some rather deep and sophisticated concepts were presented in this episode, quite sophisticated even for this show; the drawback was an unexciting narrative, even a drab pace.
 This episode always makes me wonder if this was the inspiration for the Borg. The planet has 1 ruler/leader, who’s name is Landru. But he is really just a computer. This was a common theme in the original Star Trek… computers gone awry.
 There’s also Roddenberry’s intriguing symbolism of ‘the three’, those elder statesmen, who were immune to ‘absorption’. They were among the last remaining citizens who understood that ‘freedom is never a gift’.
-Excerpts from IMDB reviews