Landru, an omniscient computer on the planet Beta III, had a near-tyrannical hold on Beta III's people until Captain Kirk put a stop to it. Kirk discovered Landru on a mission to learn what happened to the U.S.S. Archon, a ship that was lost in orbit of Beta III.
The Archon's survivors formed an underground movement against the controling Landru, an incredibly complex computer, built by and named for a scientist who lived 6,000 years before. Landru wanted to guide his people to a peaceful, civilized future, where all creative thought and instinct were suppressed. Landru created the computer in his "image" as means to enforce this ideal way of life, which made the inhabitants of Beta III part of "The Body." Landru allowed them the "Red Hour" as their only outlet for violent, emotional release.
Landru, using an elaborate system of holograms, was able to project "his image" before those not of "The Body," as Kirk and Spock witnessed. Soon after locating Landru's mainframe, Kirk realized that Landru the scientist created Landru the computer with all of his experience and memories, but none of his wisdom. Kirk used that fact to defeat the computer, arguing that instead of nuturing the planet's people, Landru was actually harming them by denying their independent thought. Processing the ramifications of Kirk's accusation, Landru overloaded and destroyed himself. And the Betans were left to work - on their own - toward developing the culture Landru intended centuries before.