Star Trek: Discovery is a prequel series currently airing, set about ten years before the original 1960s Star Trek which starred William Shatner and Leonard Nimoy. There are many things a die-hard Trek fan can point to that violate “canon”, the established history and lore about the Star Trek
universe that have been established over the half century of the
franchise’s existence.
Most of these changes are visual in nature, updating the look and feel
of the show to something that seems futuristic to a modern television
audience, instead of what would seem ten years less advanced than what
seemed futuristic to a 1960s audience. Some changes are to avoid overly
complicated lore that might turn off new viewers (although the show has
also indulged in using some of the most complicated continuity in the
franchise to tell its stories on occasion). Many of these changes can be
justified by the need to make a modern Trekshow that appeals to everyone, not just diehard fans.
But the show fucks up stardates constantly, and it’s driving me crazy.
Now, stardates might be the most inconsequential thing to complain about, the very definition of the kind of asinine nitpicking Trek fans are mocked for, but the thing about it is this: it costs Discovery
nothing to get it right.
Unlike costumes and set designs, special effects and alien make-up,
stardates are not an expensive visual, nor are they a complicated story
element that eats up exposition time. They’re just some numbers rattled
off during the traditional “Captain’s log” voice-over segments of the
show, that were originally designed to make things easier for the
writers.
Star Trek is set in the future, but exactly
when was originally left somewhat vague. Years of filling in the details
has led to the original series being pegged with the years 2265-2269. Discoverybegins in the year 2256. But the original series writers didn’t want to be bogged down with exact dates, and besides - the Enterprise
serves a United Federation of Planets: there are enough different
calendars on Earth let alone when you consider alien worlds with
different methods of measuring time altogether.
So stardates were designed as nonsense numbers that supposedly are a
kind of standard nonbiased timekeeping method in the Federation. You
aren’t really supposed to pay too much attention to them on the show, or
wonder what they mean.
However, if you do pay attention to them, presumably because you’re detail obsessed as many fans of Trek
are, you’ll notice they aren’t wholly random.
Stardates in the original series progress roughly from episode to
episode - more smoothly if you take the episodes in the order they were
produced rather than they were aired. Season 1 features dates that range
from 1312.4 to 3417.7, Season 2 runs 3018.2 to 4770.3, and Season 3’s
dates cover 4372.5 to 5943.9. Whether you watch the episodes in airdate
order or production order, the stardate progression isn’t perfect, but
it is approximate - the numbers go up, roughly 1000 units for each year
that passes in story.
With Star Trek: The Next Generation, the
franchise moved 100 years into the future, with that series set from
2364-2370, and the show’s producers paid greater attention to stardates,
with a more consistent system in place. Like on the original show,
these dates are not the responsibility of the show’s writers, but rather
are written in later by story editors and other staff members who work
consistently from episode to episode and are aware of what order the
scripts will be produced in the season. The earliest date in TNG is
41153.7. The decision had been made to increase stardates from four
digits to five to show that the new series was further in the future,
the leading number 4 was chosen as a subtle reminder the show was set in
the twenty-fourth century, the next number
was the season, and the last three numbers progress roughly from 000 to
999 throughout each season, with each season covering roughly one year
in the story. The last date in season 7 of TNG is 47988.0. This system
continued until the film Star Trek: Nemesis, set in the year 2379 on stardate 56844.9.
When JJ Abrams rebooted the Star Trek
timeline with his new films in 2009, the writers of that film decided to
just make stardates the Earth year with a decimal point after them.
Which kinda misses the whole point of why stardates exist, but at least
was easy for an audience to understand and was consistent, and missing
the point was largely the raison d’être of the Abrams helmed Trek films.
So that brings us to Star Trek: Discovery,
which - despite all the visual differences - is set within the original
continuity of the franchise, ten years before the adventures of Kirk and
Spock. Based on this, what would be a reasonable system of stardates to
assume? Perhaps to take it down to three digits, to show that we are
before the original four digits of TOS, similar to how TNG employed five
digits?
No. The earliest stardate we get in Discovery
is 1207.3, which is certainly an earlier number than the earliest TOS
given date, but based on the rationale of the previous stardate systems
would indicate a date earlier the same year as the first stardate of
TOS, not ten years earlier.
Things only go downhill from here, however. The next stardate we get is
six episodes and seven months in story later, and is 2136.8, which would
place this story in the middle of season 1 of TOS, presumably. Then the
very next episode after thatfeatures the much earlier date of 1308.9 - which again predates TOS, but only by a few weeks perhaps. And unlike past Trek
shows, where the storytelling was largely episodic and so
non-consecutive stardates in consecutive episodes can be hand-waved
away, Discovery is an extremely serialized
show. The 1308.9 episode definitely takes place after the 2136.8
episode. The next stardate we get is five episodes and nine months in
story later, 1834.2. Five episodes later, in season 2, we get 1029.46,
the earliest stardate we’ve had yet, and then in the very next episode
1834.2512, which would be about twenty-five minutes later than the
stardate from six episodes ago.
This utter nonsense, while seemingly inconsquential, demonstrates the
core of a recurring problem with Star Trek: Discovery. They want the touchstones of Star Trek, the recognizable elements, without doing any of the work for them.
They know that stardates are a thing in Star Trek,
a string of numbers with a decimal point after them, sometimes four
digits, sometimes five. Better make it four since we’re closer to TOS
than TNG, I guess. But no one is paying attention, it seems, to what the
stardates are episode to episode, whether they progress in anything
close to a logical or consistent manner, not just with previously
established shows, but more significantly in my eyes - with each otherin the same show!
Going back all the way to the original series, when you read behind the
scenes interviews with the producers, writers, and designers who worked
on it, you consistently hear about decisions that were made in at least a
desire to appear believable and coherent. “What would this thing
actually look like in the future, maybe?” or “If this was real, how
would you really design it?” It’s why the Enterprise has a smooth exterior hull for instance, instead of the highly detailed fiddly bits of ships in Star Warswhich
show scale more easily. Because if you really wanted to make a
spaceship, why would you put a ton of stuff on the outside since that
means you’d have to go out in a spacesuit to fix it?
The stardates on past series were arbitrarily decided, but then once
those arbitrary starting numbers were chosen, they progress forward
throughout the shows in a roughly consistent manner. As if they were a
real thing, that worked. And for many fans, “as if it were a real thing,
that worked” is a big appeal of the world of Star Trek. It cannot be stressed enough,it is all arbitrary fictional bullshit,
but it’s consistent within itself, and that helps us to believe it,
which helps us be invested in the stories and characters, even if they
are set on strange new worlds where no one has gone before.
On Discovery, you get the sense that the
design principles have changed from “what would seem believable?” and
“what can we afford?”, the two masters of past Trek worldbuilding, to “what looks cool?” and “what signals Star Trek
to people?” So sometimes things look familiar, like iconic props such
as phasers and communicators, other times things look utterly different,
like the overall aesthetic of Starfleet interiors or the entire Klingon
race. It’s not consistent within itself, because the goal is to either
make your jaw drop at how awesome it was, or else to signal something in
your brain that says “aha! Like on Star Trek.”
The stardates on the show are the latter - no one seems to care how
they work or if they’re consistent, but they’re a thing they know the
audience knows are a thing from Star Trek, so
let’s throw them in there, and who really cares?
What’s the most frustrating is, they’re the easiest things in the world
to get right. It’s just numbers on a page, dialogue said by an actor, it
costs nearly nothing to just make sure you’re counting up from episode
to episode rather than spouting random numbers. So when something that
small, and that easy to get right, is utterly disregarded, it puts you
on edge about how the rest of the show is being handled.
I like Star Trek: Discovery. I like the cast
and the characters a lot, I often enjoy the writing, and sometimes I
even like the aesthetic choices. But I would be lying if the feeling I
often get from watching the show is that for all the money being put
into it - and it is indeed the most expensive and thus most impressive Star Trek has ever looked - the entire series from writing to post-production feels a bit sloppy. As they say, the devil’s in the details.
"The Tholian Web" Writer: Judy Burns & Chet Richards Director: Herb Wallerstein Producer: Fred Freiberger When it comes to lists of "actually good" episodes of third season Trek, "The Tholian Web" usually comes near the top of the list, usually under "The Enterprise Incident". And it does have a ton of stuff that makes it fodder for Trekkies: new alien races, new technology, alternate dimensions, a strong Kirk/Spock/McCoy focus, and even a good showcase for the "junior officers" due to Shatner's reduced screentime.
But "The Tholian Web" is also fascinating for the way in which it examplifies an odd trend of the entire third season, which is namely the change in genre focus of the entire series. Season three is significantly more pulpy than the show was previously. There's more of the kind of sensationalist content you'd expect from the lead cover stories of old sci-fi magazines, all with a kind of bizarre horror tinge. Previously, the Enterprise explored a galaxy full of challenges and moral questions, yes, but a galaxy that makes sense. But in season three, the bizarre and unknowable rears its head for stories that are more dedicated to be unnerving and strange than to posing intellectual or philisophical dilemmas.
In this case, "The Tholian Web" is above all a ghost story. While it's heart may be the dilemmas Spock faces while in command, and learning to turn to and appreciate the advice of McCoy, the "weird" that drives the story is that Captain Kirk (and the entire abandoned starship he was on at the time) has disappeared and is presumed dead, but then begins appearing in a spectral form around the ship to several crewmen, including Uhura initially.
The complications to recovering the captain prove equally memorable, with the introduction of one of the series most unique and memorable aliens, the titular Tholians. That it took almost forty years for another one to show up in a Trek production made them ever more mysterious and noted in the minds of fandom. And ultimately the episode's true heart, the scene where Spock and McCoy view Kirk's recorded "last orders", cuts right to the kind of character interaction that ultimately made the series so beloved and remembered over the years. If the episode has an issue, it's the one that many of the episodes this season share. Namely that it doesn't have enough content to really fill it's hour, and ends up feeling slow and repetitive through a large portion of its runtime.
"The Empath" Writer: Joyce Muskat Director: John Erman Producer: Fred Freiberger
"The Empath" is a fascinating episode of Star Trek and I've been struggling with how to talk about it. Certainly it's the episode that leans the hardest into the budgetary confinements of season, producing a surreal, stage play atmosphere that might seem familiar to anyone who sat through the third season of the 1960s Batman TV show.
Kirk, Spock and McCoy are trapped by aliens with a mysterious fourth prisoner, a woman Bones dubs "Gem". She can't speak, but she is empathic, to a sci-fi degree where in addition to feeling a person's emotional states she can also touch them and absorb their pain and injuries. She literally can cure people but only by hurting herself.
The aliens who've captured them have placed them underground in a seemingly endless black void with occasional props or furniture or devices scattered about, all designed to "test" their subjects, primarily by causing them pain and then seeing how Gem responds. They particularly want to know how far she'll go in harming herself to save others, and if she can be taught to sacrifice herself for the good of strangers.
In terms of the presence of aliens in silver robes with enlarged skulls testing captive humans for an unknown purpose, this episode definitely feels like a bizarre theatrical stage play reworking of the original pilot, "The Cage", updated from 1964 to 1968. But the focus is different. The pilot was about "can we trick this depressed human into being horny enough to mate a slave class for us?", this episode is about "Is a species of empaths worth saving from annihilation, if we can discover if they can use their powers for good?"
But ultimately the minimalist sets and sparse nature of the plot means the episode becomes focused in on the show's characters, particularly it's lead trio, and showing how Kirk, Spock and McCoy all react to the situation they've been placed in, and how they feel towards Gem and towards their captors. DeForrest Kelley cited this episode as his favourite of the series and maybe it's because its budgetary limitations meant the focus needed to be on the actors, their emotions and their performances, more than the trappings of gadgets, monsters and effects.
The actress playing Gem, Kathryn Hays, was trained first and foremost as a dancer. Her performance is extremely effective. It has perhaps it's broad moments, but given that her character is mute and must carry the episode and serve as its lynchpin without dialogue, her expressions and movements must be understood to be occuring in a mime/dance tradition, furthering the "modern theatre" atmosphere of the episode as a whole.
It's an abnormal episode of Trek, but its a standout entry in the beleagured third season.
"Invasion of the City Builders" Writer: Dick Wood Artist: Alberto Giolitti The third issue of Gold Key's irregularly published Star Trek comics came midway through season three -- but the photo collage cover for this issue still uses a pre-series publicity photo of Spock paired with a still from season one's "Charlie X". The issue itself takes another tentative step towards feeling more like Trek and less like a generic pulp space adventure, and also features the debut of a new series artist. Alberto Giolitti, like his predecessor, was an Italian artist with no knowledge of the show working solely off of publicity photos. His style is very similar to Zaccara's, with very good likenesses all around, but he's not quite as good. His rendition of the Enterprise in particular isn't as gorgeous, and famously features fiery exhaust trailing behind the warp nacelles (because it's a rocket ship, right?).
In this issue, the Enterprise is journeying to planet Alpha Z-21, which is believed to be highly advanced technologically but no contact has been made with before. And I don't recall how bad it was in previous issues, but Dick Wood goes overboard on bad sci-fi terminology in this issue. Y'know the kind -- that sort of pulp sensibility of referring to money as "space dollars" and so on. In this case, a crewman tells Kirk that the ship's ETA at the planet is "two lunar hours, one galaxy minute"! What the hell is a lunar hour? Is it a 24th of a lunar day? Because just say "two days" then, man! And what the heck is a galaxy minute? If we're on lunar time (why?), why would you switch measuring scales? That's like saying I'm five feet and 12.7 centimeters tall. Why??
There's a lot of that kind of dialogue in this comic. Real haphazard half-ass stuff. Anyways whenever they manage to arrive at the planet, the Enterprise does a flyby of the planet, fiery exhaust trails and all, at an extremely low altitude. Like it's buzzing the tops of buildings. Dramatic? Yes. How the ship works on the show? Nope.
Anyways a landing party of Kirk, Spock and two nobodies beams down (still referred to as "teleporting" in this comic), and we learn what this planet's deal is -- the society became super automated with machines doing everything to the point where the machines also built the machines and those machines built the cities. Until finally themachines built more city than there were people for and now there's just a tiny bit of natural planet left and a tiny amount of inhabitants and soon the city building machines will pave over that paradise and put up a parking lot too.
Kirk & Spock meet with a local leader named Krill and pledge to help destroy the machines, teach the people agriculture, help them rebuild the planet, etc. At first Krill is skeptical, he even tries to sabotage them at one point when he feels his authority is being usurped by these newcomers, but when Spock discovers a chemical weakness in the metal the machines are made of, Krill volunteers for the risky mission to destroy them and win back his people.The comic ends with a civilization saved, quite a stark contrast to the apocalyptic ending of the previous two issues.
This is the first issue of Gold Key's Star Trek to try and do one of the series classic "social problem as sci-fi story" tales, in this case a story about over building, destruction of natural resources, and overreliance on machines. It handles it very simplistically, but then this is a comic book for children, and the fact that it tried at all raises it above the level of the previous two issues.
My question continues to be why Trek comics were coming out seemingly just once or twice a year when the show was on, and why the creative team behind the comics was only so passingly aware of what the show was like, even this far in the television run.
Rating: 3 out of 4
Next Voyage: "An alien form invades the Enterprise through Spock's mind!" in The Peril of Planet Quick Change.
"Is There in Truth No Beauty?" Writer: Jean Lisette Aroeste Director: Ralph Senensky Producer: Fred Freiberger
This episode is always tough for me to judge, because it's got some excellent sci-fi concepts and some really nice character exploration, but the execution stumbles and falls due to writing that doesn't trust the audience to figure things out for themselves.
The premise is there is an alien race called the Medusans, who are extremely civilized, culturally advanced, intellectually gifted, etc and who take to problems of navigation like a fish to water. Unfortunately their race is a non-corporeal shapeless mass of light who's form is so alien to human comprehension the sight of them drives people mad, HP Lovecraft style.
The Medusan ambassador is brought aboard the Enterprise accompanied by a telepath, Dr Miranda Jones -- played by Diana Muldaur in a rare example of a returning guest star in a different role. It kinda irks me that the series just decides to say "Oh yeah, human telepaths are a thing" out of the blue, but I guess the second pilot established ESP was legit, so that's fine I suppose. It at least established that she had to study with the Vulcans to learn to control her abilities. Anyway, she's supposed to communicate the ambassador's wishes to the humans around -- turns out she can interact with him fine because she's blind, which is played like a big reveal way down the episode's runtime (she can "see" with the aid of a sensor net she wears as part of her ensembles).
Most of the episode is given over to a few things - one is that all the men on the ship keep remarking on how beautiful Miranda is and trying to make it with her (except Spock of course). The other is that Spock can potentially meld with the ambassador due to his mental abilities but Miranda is fiercely jealous. Basically, y'know, the super "ugly" ambassador is a real chill dude, but the super "beautiful" telepath is all jealous and bitter and full of hate. Do you get the theme? Get it? Things get out of hand, and the climax of the episode is the Medusan ambassador entering Spock's body so as to interact with the crew to save the ship when it's lost in space due to a spell of madness having fallen on a character who saw the ambassador's true form.
The character study of Miranda Jones is very well rendered, an excellent portrayal of jealousy and bitterness and self-loathing. But the continual use of the words "beauty" and "ugly" to describe the various characters not only as rendering the episode's theme extremely obvious (why isn't this episode called "Eye of the Beholder"?), but also makes the Enterprise characters seem very crude. The Medusans are ugly? They're incomprehensible to the human psyche and madness inducing, but I don't know if that really qualifies as "ugly". Generally you need some kind of standard of beauty to compare to, don't you?The fact that the crew also find it, like, hard to believe that Miranda is kind of an awful person just because they're so attracted to her? I get that the message is all about like, surface level appearance versus inner character, but making the lead characters super shallow is a kind of shitty way to go about that. Seeing them all trip over themselves trying to get with Miranda isn't much fun.
The episode's pacing is occasionally sluggish, but it's balanced by the fact that this is a very creative episode in terms of its cinematic style. The relatively lightweight script is ably reinforced by inventive visual techniques, including the light patterns created for the Medusans, the fish-eye lens POV shots to indicate the induced madness, and various other novel experimentations from the usual Star Trek shooting style.
Ultimately, though, this can't save the episode, which often has a meandering feeling, creating different character dilemmas to pad out its running time, because its central idea doesn't have enough depth in it to sustain the entire hour. A bit ironic in an episode about being shallow. Rating: 2 out of 4
"Spock's Brain" Writer: Lee Cronin (Gene L. Coon) Director: Marc Daniels Producer: Fred Freiberger
Well, here we are. If there's an episode of Trek that's a punching bag, this is it. In truth, there are worse episodes of the show - but "Spock's Brain" gets special hate from fandom largely because of its unique history.
After the large effort Trek fandom went through to save the series from cancellation at the end of season two, this was the first episode to be broadcast in the third season. And for those loyal Trekkies who bothered to stay up and stay home for that 10pm premiere on Friday, this episode signalled that the series had been lobotimized just as Spock is.
This episode is written by the great Gene Coon, but since he was employed elsewhere during the third season, it's credited under his pseudonym, Lee Cronin. One could perhaps hope that if he had still been on staff this episode would have been polished more into something that explored its central ideas more, but...
This might be as good as time as any to discuss Star Trek's problem with gender equality. This is a television series that has received a lot of attention and praise over the years for its progressive, liberal, utopia vision of the future. And while the show does a fantastic job on issues of race & war, it stumbles and falls a lot on women's rights.
Part of this has to do with the show's creator. If you asked Gene Roddenberry if he felt women were equal to men, he'd definitely say yes. But he'd say it while he was hiding the side girl to his side girl under his desk because his wife's come to visit the office. This was a guy who was a womanizing alchoholic drug addict thief. And his attitudes translated into the "equal" women officers of the Enterprise wearing hemlines so high their underwear is frequently visible, and guest actresses wearing little more than the bare minimum of fabric to qualify getting on network television. Yes it was the Sixties and the Sexual Revolution, but Roddenberry was a womanizer: guest actresses were hired based on their potential lay factor for Gene.
At its core, Star Trek had sexism baked in, even if it didn't want it there.
So what does that have to do with "Spock's Brain"? Well, the story, such as it is, involves Spock's brain being stolen (without his hair even being disturbed!), and the Enterprise has to track it to an ice planet inhabited by a population of animalistic male cave dwellers on the surface and then an advanced society of women underground. But! The ultra-advanced society isn't actually run or maintained by the women, who are too dumb to understand how to work the technology, which is all automated. Unfortunatey their computer is broken, so they've stolen Spock's brain to put it into the computer to run their society.
The idea is supposed to be about how a gender fragmented society can't survive, the idea that we're stronger together than we are apart that's at the core of so much of Star Trek's ethos. But it's really not strongly explored at all, so what we're left with is that men without women are grunting cavemen and women without men are infantile idiots. The episode is more concerned with campy gags and plot machinations than exploring anything about the society itself.
It seems likely that the network chose the episode to air first because it ostensibly focused on Spock, the series' most popular character. But of course Spock is basically a brainless drone led around by McCoy on remote this episode -- an apt metaphor for Leonard Nimoy's own attitude to the series at this point.
However, if there's one thing to be said in the episode's favour it's this: the story is always moving forward. There isn't the feeling of tire-spinning one gets watching so many of these season three shows. Something happens, and then we're on to the next thing. The script may be ridiculous, with dialogue ripped from an Ed Wood movie, but it's paced well.
Another point in the hour's favour: without Spock, the rest of the cast -- Doohan, Nichols, Takei, Koenig -- all get ample time to shine and contribute. Indeed, season three overall has a better division of focus among the crew, an attempt to make the show more of an ensemble that perhaps may have developed more had the show lasted to a fourth season.
"Spock's Brain" is bad. It's a stupid plot based on a sexist theme. But it's fun, in a campy B-movie sort of way.
"And the Children Shall Lead" Writer: Edward J. Lasko Director: Marvin Chompsky Producer: Fred Freiberger
This episode. This episode is garbage. This garbage episode is a piece of garbage.
Ever see one of those "creepy children" stories? Y'know, where the kids in some small town all get weirdo powers and become creepy murder children who murder their parents and lord it over adults?
Cool. This is that, but on the Enterprise. Remember "Charlie X", back in season one? This is that, but with like five kids instead of one, and with pre-adolescents instead of a teenager, and a bunch of hocus-pocus oogity-boogity instead of character insight and examination. Oh, and the kids get their powers from an evil spirit called The Gorgon who's a glowing green old man in a giant floral print muumuu with a ruffled collar inexplicably played by non-actor Melvin Belli, the lawyer to countless celebrities from Zsa Zsa Gabor to Jack frickin' Ruby.
It's an egregiously terrible hour of television, and the first real sure sign of season three's descent into utter banality. It's also got the central problem that a lot of season three episodes do: not enough plot. There's simply not enough going on here for an hour of television. Kirk & co beam down to a planet to discover the adults are all dead and only the children alive. They beam back to the ship. The kids try to take over using spooky powers. Our heroes realize the kids more or less killed their own parents. Kirk defeats the evil spirit by getting the kids to turn on him by getting them to reconize their parents are actually dead.
That's basically it.
There's maybe something about the generation gap here, about the gulf between parent and child. But by making the kids so young as to be elementary school students, there's nothing really to be said here about the actual generation gap -- and such topics are covered much better in "Charlie X", and even later in "The Way to Eden". This episode is just garbage.
"The Enterprise Incident" Writer: D.C. Fontana Director: John Meredyth Lucas Producer: Fred Freiberger It is not a controversial statement to suggest that "The Enterprise Incident" is easily the best episode in season three. A fan favourite in a derided season, it sticks out like a diamond in the rough. A dynamite script from DC Fontana, excellent direction from Lucas, fantastic performances from the cast, this is an episode firing on all cylinders.
Coming as a response to the "Pueblo incident", this episode engages with the heightened Cold War fears of 1968 in a very intelligent way: by using the political backdrop set up as existing in the Star Trek universe. By using the Romulans and their Neutral Zone, the episode continues to build the world and also avoid the need for exposition that creating some new enemy would require.
The Romulans haven't really been seen since their debut in season one, largely supplanted in season two by the Klingons, though their memory has been kept alive by frequent dialoge mentions and occasional stock footage apperances of their vessels. In this episode, we finally get another deep dive into their intriguing and enigmatic culture and mindset. Unfortunately, we're denied another appearance by the excellent Bird of Prey ship designed by Wah Chang -- instead the show has decided to utilize the recently built Klingon battle cruiser model to "get their money's worth" from it, prompting a line in the script that the Romulans are now using Klingon ship designs. This suggests an intriguing anti-Federation alliance, but unfortunately the episode isn't interested in exploring that.
However, the story we do get is excellent in its own right. It includes Kirk pretending to be an insane gloryhound in order to give an alibi for the Enterprise crossing into Romulan space, Spock serving as a honeypot to distract the brilliant Romulan commander - who is probably one of Trek's best female characters, Spock pretending to kill Kirk, McCoy performing cosmetic surgery on Kirk to transform him into a Romulan, and the subterfuge of Kirk sneaking back onto the Romulan ship to steal their cloaking device... and getting the Romulan commander as a captive to boot.
This episode dives into the geopolitics (astropolitics?) of the Star Trek universe in a way that the original series was very vague upon, and that in general the franchise stayed fuzzy on until The Next Generation started to really hammer things down in it's middle seasons. This alone explains a large portion of its fan favourite nature, but I think there's a lot of other things at play here.
One is the appeal of seeing our heroes as "the bad guys". Like, there are legitimate defense reasons for the Federation wanting to steal a Romulan cloaking device -- but really our guys violate the treaty, commit espionage, sabotage, steal foreign property and capture a foreign officer. They're sneaking around and doing the kind of dirty work that, y'know, comes up in a navy but which the show has kept them largely free of.
But largely I think the thing that wins this episode the most fans are the interactions between Spock and the Romulan commander. D.C. Fontana - who invented the "Spock falls in love" genre with season one's "This Side of Paradise" - gives the series it's best iteration in this episode by creating a plot and characters that allow Fontana to take advantage of the sexual magnetism of the Spock character (who it was noted by the producers had the greatest percentage of female fan mail and also was the most frequently featured in various "adventures" in the fanzines) but doing so in a way that did not require a hackneyed "Spock gains emotions/goes crazy" plot.
Instead, Spock is allowed to remain his inscrutable self, the cool and aloof Vulcan. This is brilliant because it is likely this is a large part of what fans of the show found attractive about him -- a Spock who doesn't act like Spock loses the appeal (other than the ears). And through his subtle, sexually tense interactions with the Romulan commander -- herself a being of equal emotional and intellectual complexities -- we also receive our first real tantalizing clues of what the cultural relationship between Vulcans and their distant cousins, the Romulans, is like. It's a sketch, but a sketch so skillfully drawn it led to the popular Rihannsu novels by Diane Duane later in the 1980s.
This is a really fantastic episode. For Spock, for the Romulans, for D.C. Fontana, for all involved. Miss it at your peril.
