No security detail this time when Kirk, Spock, and McCoy beam down. That means there won’t be much physical danger. They’re here to evacuate some people but all they find is a quonset hut with a basement full of dust and defunct equipment.
The isolating element of this episode is a burst of cosmic rays that pose a danger to the crew of the ship, but not to the away team. This makes sense according to modern physics – the atmosphere of a planet is really incredibly helpful in defending against all sorts of radiation, but it’s a little surprising that the Enterprise, a ship of the line and the most powerful weapons platform Starfleet can field in this era, has shields that won’t protect against cosmic rays. At least, not a highly concentrated burst. You wouldn’t send people out on multi-year missions studying strange anomalies and subjected to coherent, ordered burst of high-energy weaponry if you didn’t have some ability to guard against it. This gives us an upper limit on the potency of the weapons available at the time.
Anyway, the away team gets vanished and appears in a dark room with a woman asleep on a T shaped bed. When she wakes up, she uses interpretive dance instead of saying “who are you, why are you in my room, and why are you pointing a weapon at me?” Spock declares she couldn’t have evolved on the planet, McCoy declares she’s from a species of mutes, and Kirk declares that they’re not going to hurt her while pointing a phaser directly at her face.
Then a bunch of rubber forehead aliens show up and start examining the woman, who McCoy has named Gem. And she can pick up on the nerve impulses of other people’s bodies, which also apparently means she can heal the cut of Kirk’s forehead somehow don’t ask me. She takes the away team on an interpretive dance-led tour of the facility and find the previous scientists stuck in test tubes, and three new test tubes with the names Kirk, Spock, and McCoy on them. The rubber-forehead aliens appear to be doing experiments on people.The away team and Gem run away, then see Scotty and the search party even though they’re supposed to be well away from the cosmic rays. Probably a mental projection, which might be why these aliens were given the ‘enormous cranium’ look so vital to beings with telepathic powers.
The aliens decide that Kirk alone will be a sufficient specimen for whatever it is they want to do, which apparently includes suspension bondage. It is as yet unclear why Gem gets to watch them torture Kirk or, again, why she’s not allowed to move like a normal person doing things and has to dance everywhere. The good news is she can make Kirk healthy by taking his pain from him and experiencing it herself, which she then heals. So pretty clearly the aliens are going to kill Kirk, but she’ll love him and take the death away but then won’t heal from it.
The next round involves the aliens letting Kirk choose which of Spock or McCoy will be the subject that they expieriment on next. There’s a high chance that McCoy will die. There’s a higher chance that Spock would go irretrievably insane. Too bad Kirk can’t make the decision because McCoy knocks him out with some medicine, and then deliberately does the same thing to Spock so he can keep trying to fix the remote they stole. Spock figures it out, but I guess I was wrong earlier. Kirk’s not the one who dies. McCoy is the one who’s near death.
Okay, the research aliens are apparently trying to decide which doomed planet to save, and if Gem gives her life to save McCoy, then that means her species is worthy. Of course, they violated every research psychology stricture by discussing this in freaking front of her and thereby telling her how to pass the test. Which she does, dancing out her agony but ultimately surviving the experience. That’s not good enough for the aliens, so kirk has to tell them that they’re jerks before they’ll save her planet and cure McCoy.