“The Lights of Zetar” is an episode I remember primarily from the Star Trek bubble gum collector cards I had when I was a kid (card #82 in the linked set). I remember it has a bunch of flashing coloured lights, and not much else.

The story revolves around Scotty’s girl of the week, Lieutenant Mira Romaine, who is being taken to the library planetoid of Memory Alpha. On the way they experience a space storm (the aforesaid flashing coloured lights) which affects the nervous systems of many of the crew with minor symptoms. Romaine suffers the worst, fainting. The storm moves on to Memory Alpha, and when the Enterprise arrives they discover everyone on the planetoid dead.

They return to the ship, but a transporter glitch suspends Romaine in transit for a few seconds. She reappears, with the lights flashing in her eyes. The storm chases the Enterprise around a bit, and it becomes clear the lights have possessed Mira, giving her precognitive abilities to predict how it will move. Scotty plays it down, claiming it to be some sort of space sickness. The storm enters the ship and the lights swarm Romaine, entering her body. McCoy says he has no idea how to remove them. Spock merely says that Romaine has a high level of empathy, which is probably why the lights picked her. They speak with her voice and explain they are the last survivors of the planet Zetar,and want Romaine’s body so they can continue to live.

Scotty objects and Kirk decides to drive the Zetarians from Romaine. Since none of his scientific officers have any idea how to do this, Kirk unilaterally decides to stick Romaine in a pressure chamber and jack up the air pressure. Oddly enough, this works, apparently killing the Zetarians without anyone showing a shred of regret at having wiped out the last of a sentient species. The ending is happy, except Romaine needs to leave the Enterprise to rebuild Memory Alpha, so poor Scotty will probably never see her again.

A rather blah episode. The story seems like trotting out the same old recycled plot elements again, solved by Kirk pulling a completely unheralded miracle solution out of a hat. Except for that gaping plot problem, it’s all fairly predictable and uninspiring. Poor Scotty.

Tropes: Girl Of The Week, Fainting, Spooky Silent Library, Teleporter Accident, Powers Via Possession, Space Madness, Puppeteer Parasite, Dying Race, Only You Can Repopulate My Race (kind of), Guilt-Free Extermination War, Final Solution, Ass Pull.
Body count: Everyone on Memory Alpha (killed by Zetarians), 10 Zetarians (killed by pressure).

“That Which Survives” opens with Kirk organising a landing party to investigate a strange planet that is too small, dense, and atmospherically endowed to conform to normal planetary geology. The party consists of Kirk, geologist D’Amato (fair enough), and for some inexplicable reason McCoy and Sulu. Perhaps Sulu’s earlier demonstrated fleeting passionate hobbies also includes a spot of geology. As they beam down, a mysterious woman mysteriously appears in the transporter room and kills the transporter operator, while Kirk and company can only look on as they dematerialise. They appear on the planet and immediately try to contact the Enterprise, but it’s no there! On board, the bridge crew are stunned to see the planet vanish!

It looks like some sort of Brigadoon world setup, but the Enterprise‘s replacement helm officer soon determines that the ship has actually been thrown across space almost 1000 light years. “990.7 light years” intones Spock, after no more analysis than looking at the starfield on the viewscreen. Back on the planet, Sulu attempts to explain the planet’s state by comparing it to the Tunguska event, prompting Kirk to exclaim, “If I’d wanted a Russian history lesson, I’d have brought along Mister Chekov.” The mystery woman appears on the planet and kills D’Amato, prompting Kirk to assign geology duties to Sulu. Through a futile attempt to dig a grave for D’Amato with a phaser, they discover the planet isn’t made of normal rock, but has been artificially constructed.

Replacement helm officer Rahda sets course back to the planet, saying it will take 11 hours to get there. Spock corrects her, “11.337 hours. I do wish you would be more precise, Lieutenant.” Back on the planet, the party’s concern for food and water is trumped by defending themselves against the mystery woman. Kirk and McCoy try to get some sleep while Sulu volunteers for the first watch. He immediately walks to the far side of a rock outcrop, to a location where he can’t see Kirk and McCoy – standard Starfleet watch procedure, I assume. The woman appears and attacks Sulu, but Kirk and McCoy are awakened by his screams and interfere in time to save him. Her touch disrupts Sulu’s tissues, but Kirk intervenes without being affected. They speculate she can only harm one person at a time. She later appears, saying she has come for Kirk, and McCoy and Sulu stand interposed, preventing her from reaching Kirk. This strategy seems to work fine until they stumble into a cave and find a computer controlling the planet, and it produces three copies of the woman, one to kill each of them!

On the Enterprise, meanwhile, the woman has appeared again and killed engineering crewman Watkins, and sabotaged the engines. Spock states that they have 14.87 minutes until the ship blows up – his penchant for excessive numbers of decimal places has now been fully Flanderised. Scotty needs to fix them by crawling into a duct and poking a spanner into a hatch. But wait… the ship has been subtly altered by the instant 990.7 light year flinging process, so Spock advises Scotty to reverse the polarity on the spanner! Scotty saves the day just in time and a party beam down to save Kirk and co. by destroying the computer security system on the planet. A recording of the woman (named Losira) appears and explains that her race died out ages ago, and as the last survivor she has programmed the computer to defend the station against anyone not of their species.

A moderately interesting episode, with some good moments of suspense and drama. Spoiled by the playing up of Spock’s personality quirks and the fact that they are dealing with yet another semi-omnipotent alien force.

Tropes: Vanishing Village (averted), Ludicrous Precision (3 times!), The Tunguska Event, That’s No Moon, Rock Paper Switch, Flanderisation, Reverse Polarity, Sole Survivor.
Body count: Nameless transporter officer, geologist D’Amato, crewman Watkins (all zorched by projection of Losira).

“The Mark of Gideon” is the episode I was least looking forward to rewatching. Not because it’s bad, but because this was one of the most horrifying, nightmare-inducing things I ever witnessed on TV as a child. I still get creeped out thinking about it.

It’s a story about Kirk beaming down as the first ever diplomatic envoy to be allowed on to the surface of the planet Gideon. The planet is known as a paradise with no disease and long-lived natives. Kirk beams down to the coordinates given by the Gideon High Council, and finds himself apparently back on the Enterprise, only everybody else is gone. (This is not the scary part.) Mysteriously, Kirk finds a bruise on his arm, that he has no memory of receiving. (This is not the scary part.) We cut to … the Enterprise, where Spock and Scotty are upset that Kirk seems to have vanished – never arriving on Gideon according to the Council. (This is not the scary part.) Spock requests permission to beam down and search for Kirk, but the Council refuses.

Kirk, on the empty Enterprise, comes across the lovely Odona. She has no memory of where she came from or how she got there. (This is not the scary part.) Kirk notices the ship is flying away from Gideon at warp speed, so uses the controls to drop out of warp. Odona comments that she didn’t feel any change; Kirk agrees and says that’s weird. (This is not the scary part.) Odona starts remembering bits of where she came from, saying how horrible it was, always being surrounded by people, and how nice it is being on the ship alone with Kirk. (This is not the scary part.)

They notice a rhythmic thumping sound, which Kirk doesn’t recognise as normal ship operation. He says it seems to be coming from outside, but… that’s impossible… (This is not the scary part.)

Kirk opens a viewport, and they see THOUSANDS OF PEOPLE OUTSIDE THE SHIP STARING IN AT THEM! (This is the scary bit!!!)

Arrrrrgh!!!! Arrrrrgh!!!! Arrrrrgh!!!! Arrrrrgh!!!! Even writing about it freaks me out.

We learn that the Gideon Council had Kirk beamed into an exact replica of the Enterprise on the planet, and that they are deliberately exposing Odona to some disease that Kirk was carrying, to reintroduce disease and death to Gideon. She falls ill and her father Hodin of the High Council enters the fake Enterprise to thank Kirk for helping them. He is dumbstruck as to why they would want this, surely Gideon is a paradise? Alas no, they explain, with no disease or death, their population has grown so much that the entire planet is shoulder-to-shoulder with people, and nobody ever gets any privacy. (This is not the scary part.) Kirk is aghast, wondering why they don’t use modern contraception, at which Hodin explains that they love life so much that it would be against their nature.

The questions that arise from this are numerous. If the planet is that full of people, what do they eat? Where do they grow food? How do they deal with waste? Basic hygiene? It’s obvious they’re still breeding… (This is not the scary part.)

Spock meanwhile beams down to the coordinates they sent Kirk to, and finds the fake Enterprise. He deduces its nature immediately, finds Kirk, initiates some fist-fighting with native guards, and beams up with Kirk and Odona. McCoy cures her so she won’t die, but her blood now contains the virus necessary to reduce the population on Gideon, so she returns there (this is not the scary part), parting wistfully from Kirk as the Enterprise flies away.

Actually, you know what, everything else about this story is freaky and horrible too, yet I still can’t get over that image burnt into the primal fear centres of my developing brain when I was a kid. Objectively, I’d say this isn’t a bad episode. It has plot holes and problems, but the suspense and mystery are well done. Just don’t make me watch it again.

Tropes: Accidental Nightmare Fuel, Ontological Mystery, Amnesiac Hero, Ass In Ambassador, Gaussian Girl, Jungle Drums, Population Control, Empire With A Dark Secret, Who Wants To Live Forever?, Nobody Poops, Depopulation Bomb.
Body count: None!