Also having a female helmsperson for once.
And Lee Meriwether was good and garnered sympathy as the "enemy" seeming to regret the murders.
The basic story I can see made as a Next Gen episode, minus all the talk about "oh she's so beautiful and yet so evil" That basic story, sized up briefly at the very end, mostly as guesswork from McCoy?... is interesting, and gets overwhelmed by the tacky attempts to amaze us with Lee Meriwether's ethereal deadly beauty.
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I hated that costume, till as an adult it started to make me think of early Earth civilizations, which must have been the point. Still, sometimes original Trek really managed to undermine beauty while wanting us to be amazed with it. Sometimes it was a fairly ugly costume like this, sometimes it was hair pulled back so tightly in a bun that the actress's face looked skull like...
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The crisis with Spock and Scotty working to stop the ship from exploding, classic Trek scene. Isolate that part, and you'd never know it was supposed to be from a "bad" episode.
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I always loved the weird turning-on-edge disappearing effect, plus that music.
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I'd have kept that, given Lee M something less tacky, more dignified to wear (revealing or not revealing), and given her recorded self more exposition at the end. A hologram of her in her surroundings, maybe showing life before things went wrong, all that would have been perfect.
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So many rough edges... like the crew moving and watching Lee while in the transporter beam... Ivan Dixon's replacement on Hogan's Heroes giving perhaps the worst reading of one of the worst lines ever on Trek...
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I actually envy Gene Roddenberry's (I assume that's where the attitude comes from) ability to be SO in awe of the ethereal wonder of feminine beauty that he can show the crew brought to their knees in wonder at it. Thing is, they'll moon over the beauty of a guest star... then return to working side by side on the ship with women professionals who are every bit as beautiful, without being bowled over by them. And the womens' uniforms beat the guest stars' costumes by a parsec.