The PowerTrio beams down to a planet in the Minarvan system to rescue a pair of Federation doctors before the sun goes supernova. The doctors are nowhere to be found, but an audio/visual record they left behind reveals they seem to have vanished into thin air accompanied by an earthquake and an ear splitting buzz. Soon, our heroes are experiencing the same thing.

[[YouWakeUpInARoom Fade from black]]. Spock's reading indicates that they are either on the set of a minimalist avant-guard play, or they're several miles below the planet's crust. They find a lovely brunette with a pixie cut and a diaphanous gown taking a nap. They wake her up to find that she is mute. Bones decides to call her Gem. (No relation to a [[{{Jem}} truly outrageous pop star]] or a young character from ''Literature/ToKillAMockingbird'') Soon after, they are introduced to their hosts, a pair of SufficientlyAdvancedAliens named Thann and Lal. (No relation to [[Recap/StarTrekTheNextGenerationS3E16TheOffspring a certain android who learned to feel]])

Doctors Ozaba and Linke are now physicians under glass. Lal and Thann maintain that [[BlatantLies they had nothing to do with their deaths]]. They have experiments to do, and now they have three new lab rats. They even have neatly labeled glass cases in the event that they don't survive the experiments!

!!Tropes from this episode include:

* ActOfTrueLove: [=McCoy=] sacrifices himself to protect Kirk and [[VitriolicBestBuds Spock.]]
* BlueAndOrangeMorality: The Vians must have some form of compassion if they are willing to rescue a race from a supernova sun. Yet, their test to see which one is more worthy of saving is needlessly cruel.
* BookEnds: The scientists quote a Bible passage during the teaser, while Scotty recounts the story of the Pearl of Great Value, which while not identified as such, originates as another passage at the end.
* ColdBloodedTorture: The Vians call it an [[InsistentTerminology "experiment".]]
* CuteMute: Gem, with her pixie cut and modest if diaphanous outfit, is more cute than sultry. Her constantly startled expression adds to her cuteness. She has no vocal chords and never utters a sound, even her weeping being silent.
* DeadpanSnarker: The values of emotion are discussed in the epilogue. Spock is told that perhaps Vulcans could learn something about the importance of emotion. "I shall give the thought all the consideration it is due." Spock replies. Bones' complement of Spock's bedside manner could count as a deadpan snark as well.
* EmotionsVsStoicism: A major theme of this episode. The force field Kirk and Spock are kept behind is triggered by their emotions. Spock is able to suppress his enough to walk through it.
* TheEmpath: Well, duh! Look at the title!
* EmpathicHealer: Gem, and her decision of whether to risk her life to save Dr. [=McCoy=] is a major plot point.
* FriendshipMoment: Bones knocks out both Kirk and Spock in order to sacrifice himself to the Enemy of the Week.
* HealingHands: Gem has to touch people, and let their pain flow momentarily into her, in order to heal them.
* HellIsThatNoise: The sound that attacks everyone's eardrums just before they disappear and awaken in the Vians' "lab" for want of a better word.
* HeroicSacrifice: Kirk offers himself up to save Gem and his friends. While Kirk is sedated, Spock declares himself in charge of the mission and decides that he will give himself over to the Vians. Bones sedates Spock and offers himself up. Gem's entire race will be destroyed if she is not willing to sacrifice herself to heal Bones.
* HeyYou: Name dropped when Bones defends his idea of calling the female alien Gem with "It's a lot better than 'Hey you'."
* HomeworldEvacuation: The star of the Minarva system is about to go nova. A group of highly advanced aliens known as the Vians can save the population of only one of the planets in the system. They decide to determine which planet's population will be saved by putting a member of each population through a SecretTest.
* HopeSpot: Hey, look! Scotty and a pair of RedShirts are here to save us! Nope, just a mirage set up by those darn Vians.
* HumansAreSpecial: That's what the Vians learn from their "experiments".
* ImADoctorNotAPlaceholder: Bones would like to remind you that he is neither a coal miner nor a mechanic.
* LiquidAssets: Gem can heal others, but suffers concurrent damage to herself. If she heals someone badly enough injured, she could die.
* MoreExpendableThanYou: The Vians intend to use either Spock or Bones for an experiment that is highly likely to cause death or permanent insanity. Spock declares that he is volunteering; Bones overrules that decision with a sneak knockout shot.
* NeverMyFault: When accused of killing the two doctors, the Vians insist it was their own physical weaknesses that killed them. It was their fault for not being immortal!
* NoodleIncident: Bones mentions that the sleeping woman they find looks harmless. Spock points out that people have said the same before being attacked by rock crystals. When the Hell did that happen, Spock?
* OntologicalMystery: [[Music/TalkingHeads How did we get here?]] This is not our red sheeted bed. This is not our beautiful healer. These are not our specimen jars. (OK, they have our names on them....)
* PartingFromConsciousnessWords: "My decision still stands" says Spock when Bones shoots him up with a sedative, taking the decision of who will be tortured out of Spock's hands. (He was going to offer himself.) "Good bedside manner, Spock." Bones tells Spock just before he passes out from his injuries.
* PlotHole: Gem has no problem absorbing, then apparently instantly healing Kirk's wounds. Why can't she absorb just part of [=McCoy=]'s injuries and heal him in stages?
* PrematurelyMarkedGrave: a variation; the PowerTrio find two scientists dead in experiment cases and three more cases with their names.
* PsychicPowers: Gem has them in the form of HealingHands. It is unknown whether other members of her race have this ability or if she is unique.
* RubberForeheadAliens: Lal and Thann. Seriously, Will, what's up with the glittery Hefty bags?
* SadisticChoice: Kirk is told he must give either Spock or Bones up to be tortured as he was earlier. He decides to TakeAThirdOption and offers himself.
* ScrewYouElves: Kirk gives Lal and Thann a good [[KirkSummation Him Summation]] when the "experiment" is finally over.
* SingleTear: Gem sheds one when she realizes what these three men are willing to go through for each other. She breaks down in tears when she finds out just how tough it will be to heal Bones' extensive injuries.
* SomeKindOfForceField: Prevents our heroes from interfering with the "experiment".
* SecretTestOfCharacter: The Vians can only save one planet when the sun goes supernova and wanted to see if Gem's people were worth saving, all based on her decision to save another's life.
* TheVoiceless: Gem. Justified in that she has no vocal cords.
* YouSaidYouWouldLetThemGo: Said by Kirk after he offers himself up to the Vians. Bones and Spock are, as they say, safe. For now.