Several weeks overdue for R&R, the Enterprise
arrives in orbit above a pastoral Class M planet with no signs of life. Kirk orders several landing parties down to determine its suitability for shore leave. Sulu and McCoy go down but when they split up, McCoy sees a large white rabbit being chased by a young girl named Alice. McCoy yells for Sulu but by the time he shows up girl and rabbit have both disappeared into the bush. McCoy calls up to Kirk, and the captain suspects that the doctor is trying to lure him down but goes along anyway after Spock gives him a gentle prodding.
Oh, my paws and whiskers! I'll be late.
On the planet, McCoy and Kirk track the rabbit's footprints while in the brush a rock rolls aside to reveal an antique revolver. Kirk cancels shore leave and they conduct a more thorough exam of the planet. He's interrupted when they hear gunshots. He and McCoy go to investigate and find Sulu test-firing the revolver he discovered. Sulu says it's just like a gun he was thinking about that he needed for his collection. They then try to find the rabbit and Kirk talks to McCoy about how the fact that he thought McCoy was initially playing a prank remind him of the pranks that an upperclassman named Finnegan played on him at the Academy. They split up to follow the tracks and suddenly Finnegan himself shows up and slugs Kirk. The captain prepares to fight but is forced to leave when he hears a woman's scream. He and the others find Yeoman Barrows, claiming that a cloaked man resembling Don Juan attacked her and ripper her dress. As hidden antenna secretly track them, McCoy tries to reassure Barrows who says she was thinking about Don Juan, while Kirk goes to find Sulu. He's distracted by some flowers and thinks about his first love, Ruth. She appears and kisses him, but doesn't appear to have aged in 15 years.
Ruth, how can it be you? How could you... possibly be here? You haven't aged. It's been 15 years.
It doesn't matter. None of that matters.
McCoy interrupts Kirk to report that they've spotted birds, despite the fact that they initially detected no signs of life. A distracted Kirk finally orders the landing party to assemble at the beam down spot and reluctantly says goodbye to Ruth. Spock calls down to report that they've detected highly advanced power readings that are interfering with the ship's operation, and indicate an advanced civilization somewhere on the planet.
Getting strange readings from the planet's surface, Captain. Some sort of power field down there.
McCoy and Barrows are flirting and he talks about how he should treat her as a princess. A princess' dress appears on the bushes in front of them, and Barrows believes McCoy left it there. He goes along with her as she changes into it, while another landing party member, Rodriguez, calls McCoy to pass on the captain's assembly order. However, the same power field is interfering with the communicators. Rodriguez is forced to break off when a tiger suddenly appears to menace him and his companion, Mary Teller. However, the tiger wanders off and they manage to escape.
My dear girl, I am a doctor. When I peek, it's in the line of duty.
Kirk spots the birds and refuses to beam down a security team since so far there's been no danger. However, a samurai warrior emerges from a hidden door to attack Sulu, and the lieutenant discovers his phaser doesn't work. Sulu manages to escape and meet with Kirk, and Spock beams down just before the power cuts off the transporters. They hear a tiger roaring in the distance and go to check it out. Meanwhile, a black knight appears to challenge McCoy when he talks about a black knight in the context of Barrows' medieval dress. Believing it's a hallucination, he stands there as the knight charges him... and stabs him through the chest, killing him. Kirk and Spock arrive only to discover that their phasers aren't working. Kirk uses Sulu's revolver to bring down the knight, and they discover that "he" is actually some kind of android made out of celluloid matter. Spock concludes that each creation is just as real... and potentially deadly, as the original.
These things cannot be real. Hallucinations can't harm us. Go back to where you were.
Rodriguez and Teller are heading for the rendezvous when a Japanese fighter plane from Earth's 20th century starts a strafing run, killing Teller. At the glade, the black knight and McCoy disappear when no one is looking. Spock asks Kirk what he was thinking when Finnegan and Ruth appeared. When Kirk mentions Finnegan, the upperclassman appears again and Kirk runs after him into the mountains. The two fight but Finnegan hasn't aged and initially beats up Kirk, knocking him out with a trick. When Kirk wakes up, he demands answers but Finnegan refuses to explain anything. Kirk finally knocks him out and is clearly satisfied despite the beating he's taken. Spock finds him and determines that Kirk has achieved one of his heart's desires. Spock says he has come up with a theory: the planet is somehow making their thoughts real. However, when Spock mentions the tiger it appears and the two officers slowly back away. They head back for the landing party, dodging Rodriguez's Japanese fighter and Sulu's samurai warrior.
You never could find your head with both hands!
At the glade, Barrows thinks of Don Juan again and the figure appears to attack her. Sulu and Rodriguez drive him off and Kirk and Spock arrive. Kirk has them all snap to attention and limit their thoughts, but an elderly man appears out of the bushes. He explains that he is the Caretaker of the planet and identifies them by name. He apologizes, saying that he was initially unaware of the Enterprise
's arrival and didn't realize they were unaware of how the planet functioned. Spock realizes that the planet is a sophisticated "amusement park" that the Caretaker's people created to provide themselves with amusement. Kirk isn't satisfied with the answer, since McCoy is dead. However, the doctor shows up with two attractive "women," and explains that he was taken below the planet's surface and healed in an advanced medical facility. The Caretaker refuses to explain about his people but invites them to take their shore leave on the planet, and adjusts the power field so the ship is no longer incapacitated. Kirk agrees and prepares to head for the ship, but when Ruth arrives he decides to stick around.
The term is amusement park.
Of course. An old Earth name for a place where people could go to see and do all sorts of fascinating things.