responds to a distress call and finds a peaceful uninhabited planet but with traces of metallic debris. Kirk, Spock, McCoy, Yeoman Leslie Thompson, and Lt. Shea beam down to the planet and find two human-looking individuals, a man and a woman, wearing uniforms and high-tech belts. They tell Kirk to surrender the Enterprise
and use their belt devices to immobilize the landing party. The man, Rojan, informs him that he is the commander and that they are hijacking the Enterprise
Once Rojan and his associate, Kelinda, disarm the landing party, they free them from the paralysis and explain that they are Kelvans from a planet in the Andromeda galaxy. Radiation levels will render their galaxy uninhabitable within ten thousand years and his group and others were sent out to find new inhabitable galaxies. Kirk warns it will be difficult for them to take the Enterprise
but Rojan’s three other party members have already transported themselves up and paralyzed the entire crew, taking control. Roan tells his people to start modifying the Enterprise
so that it can penetrate the galactic barrier and travel at sufficient speed to reach Andromeda in only 300 years. The Kelvans’ own ship was destroyed penetrating the barrier. Rojan refuses to hear of a peaceful solution, saying they are conquerors and won’t compromise. He imprisons the landing party in a cave with impenetrable metal bars, to use as hostages if need be.
We do not colonize. We conquer. We rule. There's no other way for us.
McCoy and Spock have analyzed the tricorder readings and determine that the Kelvans have perfect human bodies, but the odds are astronomical that they evolved to human shape. Concluding that the Kelvans must have a central power generator for their belt devices, Kirk has Spock try to make mental contact with Kelinda, their guard. Spock is thrown back but Kelinda comes in and Kirk knocks her out and takes her belt device. However, Rojan immobilizes him as soon as they leave the cave and takes it back. As punishment, Rojan converts Shea and Thompson into small compressed dodecahedrons... and then destroys Thompson and restores Shea.
The remaining landing party is returned to the cave where Spock explains that he senses the true mental image of the Kelvans: hundred-armed tentacled creatures who have taken human form to use the Enterprise
. They come up with a new plan to use McCoy’s medical equipment to jam the Kelvans’ generator but need to get up to the ship. Spock feigns near-death by going into a relaxation trance and McCoy convinces their guard to beam them up to Sickbay where another Kelvan, Tomar, watches them. McCoy gives Spock a (fake) shot to satisfy Tomar and once Spock awakens, they go to work.
Rojan meets with Kirk and tires to convince him there’s no point in further resistance. Kelinda admires the flowers and Kirk notices her interest in the sensations. Rojan then takes Kirk and Shea up to the Enterprise
and they head for the Galactic Barrier at higher-than-maximum speed. Spock, McCoy, and Scotty have determined where the generator is but can’t penetrate its casing. Without any other options, Scotty and Spock suggest they blow up the Enterprise
rather than let the Kelvans complete the mission. Scotty has already rigged the anti-matter nacelles to destruct.
They enter the barrier and Scotty awaits Kirk’s order, but he refuses to destroy the ship. Once they’re through the barrier, Rojan orders his people to commence “neutralization.” To eliminate any possible threat and maintain food supplies, all non-essential Enterprise
crew are turned into dodecahedrons. Only Kirk, McCoy, Spock, and Scotty are considered “essential personnel.”
While the remaining men go to the mess hall to try and figure out what’s to do next, Tomar comes in and demands they explain “eating” to him. Tomar digs in, enjoying himself, and Spock notes that the Kelvans don’t have any human senses in their natural forms. Kirk figures that since they’ve taken on human form, they are now subject to normal human reactions and they can use that to distract the Kelvans and get their belt-devices. Scotty starts by taking Tomar to his cabin and introducing him to the joys of hard liquor.
McCoy works on another Kelvan, Hanar, saying he needs vitamin shots while injecting him with a stimulant. Kirk starts on Kelinda, apologizing for knocking he out and then kissing her. Initially reluctant, she soon becomes intrigued by the sensation but breaks it off when Rojan comes in. Kirk leaves and Kelinda tries kissing Rojan without any success.
Do you really regard this touching of the lips as pleasurable?
Later on the voyage, Spock and Rojan play chess and the Vulcan goads the Kelvan into reacting jealous at the thought of Kirk and Kelinda together. Rojan tells Kelinda to stop seeing the captain but she refuses and goes to visit him. While Scotty and Tomar get progressively more drunk, the over-stimulated Hanar snaps at Rojan on the bridge and is confined to his quarters. Kirk and Kelinda start kissing again while Spock mentions to Rojan that the two are together again.
Scott finally manages to drink Tomar under the table and get is belt-device... but passes out unconscious himself at the door. Rojan barge in on Kirk and Kelinda and starts a fistfight. Kirk holds him off and points out that after even a short time the Kelvans are acting like humans: by the time they arrive at Andromeda in 300 years they’ll be completely unrecognizable as Kelvans. Rojan finally calms down enough to concede the point and Kirk offers them refuge as peaceful allies. Rojan considers the matter and accepts, agreeing to send a robot ship on to Andromeda to inform his people of the arrangement. Meanwhile Rojan and his people will start by colonizing the planet the Enterprise
found them on. As Rojan and Kelinda kiss, Kirk orders the Enterprise
to head for home.