enters orbit around M-113 and Kirk, McCoy, and Crewman Darnell beam down for a routine medical examination of Dr. Crater and his wife Nancy… who is McCoy’s old flame. The planet has a number of archaeological ruins and Crater and his wife are conducting a dig. They go into the Craters’ quarters and McCoy wonders about how he let her go. Nancy arrives and McCoy thinks she hasn’t aged a day. She appears substantially older to Kirk, and a totally different attractive woman to Darnell. Taken aback, Kirk orders him outside and after Nancy leaves to get her husband, she entices him into following her.
Something wrong, Darnell?
Excuse me, sir. Ma'am, if I didn't know better...
I'd swear I knew you on Wrigley's Pleasure Planet. You're exactly like a girl...
Crater arrives to greet Kirk and McCoy… and tell them to leave. He demands extra salt tablets for the heat but otherwise doesn’t see any reason for them to be there. Kirk overrides him and Crater realizes McCoy used to know his wife. He seems pleased that Nancy has someone visiting her that she knows. McCoy comments on Nancy’s youth and Kirk contradicts him, and McCoy seems temporarily taken aback. They hear a scream and run out to investigate, and they find Nancy standing over Darnell’s body. Kirk fishes a root out of his mouth while noticing the odd red mottling on his face in the shape of rings. Nancy claims she saw Darnell eat the root and tried to stop him, but she was too late. Crater insists they leave but Kirk postpones the examination and has Darnell’s body beamed up. Nancy also seems curiously insistent about making sure they get salt tablets.
I noticed he had a Borgia plant in his hand. Before I could say anything, he--
taken a bite from it...
his face all twisted...
Aboard the ship, Spock determines that the plant is indeed poisonous, but there’s no record of it causing mottling. McCoy concludes that Darnell wasn’t poisoned and there’s no visible cause of death. McCoy admits that Nancy initially looked younger to him, but then appeared her correct age when he saw her.
There were bits of the plant in his mouth. Jim, he could not have swallowed any. My instruments
would have picked up any trace. I tell you, this man shouldn't be dead. According to all the
he should get up and walk away.
Kirk decides to remain in orbit to investigate the matter, and McCoy reports that Darnell’s body was entirely drained of salt. McCoy worries that he might have missed something due to his interest in Nancy, but Kirk dismisses his concern and notes that the Craters were interested in salt. They beam a party down to the planet and Kirk demands to see Nancy, who is supposedly out at another dig. Kirk sends Crewman Green to find her and another crewman, Sturgeon, to collect samples of the poisonous plant. Crater doesn’t seem concerned for his safety or attach any significance to the fact they need salt. Kirk orders the Craters aboard the ship despite Professor Crater’s objections, while Spock confirms the plant couldn’t have caused Darnell’s death. Crater sneaks out and finds Sturgeon’s corpse. He calls out to Nancy, who is hovering over the dead Green, and promises her salt.
Nancy! You! Salt! I've got salt! Smell it! Smell it, Nancy!
Crater runs off while Nancy takes on the form of Green and reports to Kirk and McCoy. They beam up to the search to conduct a more thorough search and “Green” runs into Yeoman Rand, who is delivering a food tray with salt. He jumps into the turbolift with her, while Spock detects only Crater on the planet, searching for something.
Why don't you go chase an asteroid?
Rand goes to the botany lab where Sulu is working and Green follows her in. Sulu’s plant reacts to Green and he quickly leaves. Spotting Uhura, he takes on the form of a different crewman, like someone she was thinking of. He speaks in Swahili but before he can get closer, Uhura is summoned to the bridge. Uhura seems almost hypnotized but Sulu and Rand come out, breaking the spell.
Her name's Gertrude.
No, it's a he plant. A girl can tell.
McCoy is trying to sleep in his quarters and Kirk prescribes a sedative for him. McCoy takes a pill, while Spock confirms Professor Crater is the only person on the planet. Kirk and Spock beam down while Nancy takes on her female form and goes to visit McCoy. She says he has stronger memories then tells him to get some sleep. Rand and Sulu find a dead crewman, with the same red mottling on his face.
The others--I don't relate to them as much. You have such strong memories of me. You do
care, don't you, Leonard? It makes me feel so...
McCoy dozes off as a shipwide medical alert is called. Nancy then takes on McCoy’s form. Kirk and Spock close in on Crater, who tells them to go away, and they find Green’s corpse and realize an imposter is aboard. They try to take Crater alive but he opens fire on them with a phaser, trying to frighten them away.
He's just trying to frighten us...
and he's doing a pretty good job.
“McCoy” shows up on the bridge and offers his help. Kirk flanks Crater while Spock provides a diversion, and Kirk stuns the professor. A dazed Crater explains that “she” was the last of her kind and needed salt to survive. It accidentally killed his wife a year or two ago, but Kirk isn’t impressed and beams him up to the ship.
The Earth buffalo.
What about it?
Once there were millions of them...
prairies black with them. One herd covered three whole states...
when they moved, they were like thunder. And now they're gone.
Kirk calls a meeting with Nancy/McCoy present and they discuss the situation. McCoy advises them to try and approach the creature peacefully. Crater is there and clearly recognizes McCoy as the creature, but refuses to identify it for Kirk, insisting it needs love as much as it needs salt. Kirk orders McCoy to use truth serum and Spock goes with him. A few minutes later Kirk is called to sickbay where Spock was injured when “McCoy” attacked him. The creature killed Crater and tried to kill Spock, but his copper-based blood repelled it.
This thing becomes wife, lover, best friend...
wise man, fool, idol, slave. It isn't bad to have everyone in the universe
at your beck and call. You win all the arguments.
Nancy returns to McCoy’s quarters and takes on her female human form. She begs him for help and Kirk arrives with a phaser. He also has salt and tries to lure it into revealing its true form. She tries to get McCoy to send Kirk away but she can’t resist the salt and McCoy gets in the way. She then hypnotizes Kirk and starts feeding on him, and Spock wrestles with McCoy for the phaser. When he refuses. Spock tries to knock out the creature physically but it's too strong. When he finally accepts it’s not Nancy, it reverts to its alien form and McCoy shoots it, saving the captain. It assumes the Nancy form one more time and begs for mercy, but McCoy kills it. Later, they prepare to leave orbit, while Kirk considers the plight of the buffalo.
Something wrong, Captain?
I was thinking about the buffalo, Mr. Spock.