“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).