|Season 1, Episode 15|
|Air date||December 29, 1966|
|Written by||Theodore Sturgeon|
|Directed by||Robert Sparr|
|Balance of Terror||The Galileo Seven|
|Star Trek episodes|
Kirk decides to give his crew a much needed shore leave when they find a deserted but idyllic planet. But there is something ... odd about this planet and Kirk and his crew will find themselves facing their wildest fantasies and their darkest nightmares...
Stardate: 3025.3 Sulu likes the placeAfter many months of traveling, the crew of the Enterprise is given a vacation. For their vacation, an uncharted planet is selected. Before anyone leaves the ship, the planet is scanned for lifeforms and is found to be uninhabited. Then, McCoy and Sulu are sent down to do recon of the planet life and the conditions of the planet. While on the planet, McCoy finds a giant white rabbit with a gold watch and blonde girl chasing the rabbit. Soon Kirk and Tonia Barrows are beamed down as well. When Kirk lands on the planet, he finds a man named Finnegan who had bullied him in the days when he was in the academy. Finnegan provokes Kirk and leads him on a wild goose chase. Kirk soon finds Ruth while on the chase and notices she has not aged at all despite it being 15 years since he had last seen her. Meanwhile, the other crewmen are dealing with other oddities such as samurai warriors and tigers. As time goes on, communications between the USS Enterprise are getting weaker. McCoy is dead Spock beams down the planet after communication between the Enterprise and the men on the planet become impossible. Kirk calls for the crewmen on the planet to regroup at a certain location. McCoy is the first to reach the rendezvous point and encounters a knight. Believing that all he had been seeing was an illusion, McCoy does not get out of the way when the knight charges at him. He is impaled and dies. Spock and Kirk arrive at the scene and kill the knight using a revolver that Sulu had found earlier. When they examine the knight, they find that it is manufactured like the plants and other things on the planet. Later, when bodies of both person had disappeared, Spock comes to the conclusion that whether they are thinking is being created on the spot. Kirk starts thinking of Finnegan once more and Kirk pursues him to fight him once more. Kirk laughsAfter Kirk defeats Finnegan, he gathers all of his crew members and finds a way to counter act what had been happening to them on the planet. He orders them to concentrate of being alert and attentive. An old man then appears and tell Kirk and his crew that they are on a planet designed to be an "amusement park." The old man then shows Kirk that the effects of the fantasies are not permanent. Suddenly, McCoy appears with two women at his side. Kirk realizes that the place could be delightful if the person is warned before entering. He allows his crew to leave the ship and enjoy their vacation on the planet. Spock volunteers to head back to the ship, but Kirk stops him. He then changes his mind and stays when Ruth appears.
Theodore Sturgeon's original script for this episode was rejected by NBC because it was considered too imaginative and would be more expensive because of it. Because of that, Gene Roddenberry had to make quick changes to it. Unfortunately, he was rewriting the during the production of the episode. Actors would have little time to memorize the new lines and they were forced to adlib some of the scenes.