Balance of Terror

In a well made take on an old submarine flick called The Enemy Below, Kirk must out wit and out manuver the Captain of a cloaked Romulan scoutship, and prevent it's return to Romulan territory. They discover that the mysterious Romulans resemble Vulcans, and that the Romulans and Vulcans are from common descent.
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Shore Leave

Kirk, McCoy and Sulu, and a full landing party beam down to a beautiful but unknown planet to check its suitibility for shore leave. They find that the people they are thinking about are being manufactured, and soon discover that this is both pleasurable and dangerous.
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The Galileo Seven

The Shuttlecraft Gallileo goes down on a class M planet in the middle of Murasaki 312, a quasar-like phenomenon. Spock, in command must try to get the ship operational while fighting off giant indigenous aliens.
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The Squire of Gothos

Trelane takes Kirk and Sulu prisoner, and considers the Enterprise and her crew to be his toys. He is an omnipotent child, whose parents eventually show up and make him let the Enterprise go.
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