#9 on my top 20 list is "The Naked Time," a tense, emotional hour that strips raw the series' characters, and reveals their inner faces.
This is the episode that lays bare Spock's guilt about never being able to tell his mother he loves her, and explores Kirk's obsession with the Enterprise. We also see Sulu as the mad, and dashing, swordsman.
More importantly, this episode -- which concerns a disease stripping away inhibition -- is "a standard" for Star Trek, meaning similar, or identical plots appear in the spin-offs. (See: "The Naked Now.")
The episode also introduces the possibility of time travel to the series.
The U.S.S. Enterprise (NCC-1701) orbits distant Psi 2000, an ancient world on the verge of breaking up. The crew's mission: to recover the planet-bound science team, and monitor the disintegration of the planet.
Unfortunately, the landing party (consisting of half-Vulcan science officer Spock [Leonard Nimoy] and Joe Tormolen) discovers that the entirety of the science team is dead...and dead under very odd conditions indeed.
One woman has been strangled. An engineer is dead at his post, frozen to death because life support was de-activated, and another man died in the shower fully-clothed.
Tormolen unwittingly brings this unique form of "space madness" back to the starship after removing a protective glove (to scratch his nose...), and coming into contact with a contaminated console.
This "disease" spreads rapidly aboard the Enterprise as Captain Kirk and the others see "hidden personality traits forced" into the open among their comrades.
This symptom means that Mr. Sulu (George Takei) becomes a swashbuckler.
This means that Nurse Christine Chapel (Majel Barrett) confesses her undying love to Mr. Spock.
Even the logical Mr. Spock is infected too, lamenting the fact that he could never tell his mother that he loved her. Kirk is not immune, either. He admits the personal cost he's paid to serve as captain of the Enterprise, not the least of which is his isolation from the men and women he leads.
"No beach to walk on," Kirk muses wistfully.
Soon, events spiral out of control. A contaminated Lt. Kevin Riley commandeers Engineering and shuts down the engines. This means that as the planet breaks up, the Enterprise can't escape orbit. Scotty (James Doohan) proclaims dramatically that he "can't change the laws of Physics" and re-start the engines cold.
Things look grim until Kirk snaps Spock out of his crying jag. Once rational again, Spock realizes that there is a formula for cold engine start up, one that has never been tested.
In the end, Dr. McCoy (DeForest Kelley) finds a cure for the disease, and the Enterprise barely escapes Psi 2000 as it cracks up, utilizing a dangerous new intermix formula which generates a time warp.
"The Naked Time" (By John D.F. Black and directed by Marc Daniels) is not just an exciting Star Trek story from early in the series' historic first season, but the prototype and creative wellspring for much of episodic science fiction television.
In essence, "The Naked Time" finds a useful plot device -- here an alien molecule/disease that acts on the human blood stream like alcohol intoxication -- by which the writer can excavate the hidden, buried, or repressed facets of the lead characters. This is important because there are things that characters will never realistically reveal to others, all things being equal.
All things aren't equal, here, however, and the characters reveal new, deeper shades.
Star Trek went back to this "Naked Time" well at least a few times over is three seasons, with variable results. "This Side of Paradise" employs alien spores to give Spock a love story, to great emotional effect.
Oppositely, the third season's "And the Children Shall Lead" uses Gorgon-powered evil tykes to reveal that Uhura is afraid of aging, and expose Kirk's fear -- again -- of losing command. That episode is generally considered one of the worst of the series
Star Trek: The Next Generation went boldly where the original series had gone before in a story called "The Naked Now" in 1987, which revived the threat (alien disease) to vex the crew of the Enterprise-D. Ironically, the disease there seemed to reveal less diverse behavior among the crew; basically that all the women on the ship (Crusher, Troi and Yar) were sexually-deprived. The answer to this deprivation, amazingly, was more suppression. Captain Picard opined in the episode's coda that they would make a fine crew "if" they could "avoid temptation."
Another facet of "The Naked Time" that bears repeating: technically, it's the first time travel episode on the classic series.
Spock develops a formula that sends the Enterprise back in time three days, or seventy-one hours.. In the final scene, he says to Kirk that time travel is now longer a theory but a reality. Kirk opens up the door to a whole bunch of stories by replying "we may risk it some day."
Ironically -- despite the overt set-up here -- follow-up Star Trek time travel stories utilized a different method of time travel all together: a slingshot around the sun at high warp velocities. This technique appeared in "Tomorrow is Yesterday," "Assignment: Earth" and Star Trek IV: The Voyage Home.
Focusing on the episode itself, "The Naked Time" expresses something unique and very individual about the series, and this may element prove the dividing line between adherents and detractors.
Specifically, all the havoc in the episode commences when Tormolen takes off a glove to scratch his nose, and is contaminated by the infection. Some people will complain about this plot point. They'll ask: how did a man ascend to a position of authority on board the U.S.S. Enterprise, after presumably rigorous training in Starfleet, and then turn around and do something so stupid, so thoughtless, so reckless? I sympathize with those literal-thinkers who have a problem with this.
However (and this is where I fall on the subject), the glory of the original Star Trek (and one largely sacrificed to catsuits and soap opera plotting in later generations), is the continuing recognition of mankind's foibles.
Humans do make mistakes from time-to-time, and many stories in the original Star Trek canon are possible only because humans do something wrong, or reckless, or silly. I happen to appreciate this facet of "The Naked Time" and Star Trek. I believe that even when we reach the stars, we'll still be the same flawed creatures we are today. That doesn't make us bad. As Kirk would say, it just makes us human.
What else happens in "The Naked Time"?
Well, Nurse Chapel alludes to some kinky rumors about Vulcans. "The men from Vulcan treat their women...strangely," she muses with a look that suggests she wouldn't mind playing the willing victim if Spock were her victimizer. This is another reason I love the original Star Trek series: it can be downright perverse and kinky.
We learn from Kevin Riley that there's a bowling alley on the Enterprise. That's a little strange. So TV doesn't survive past 2020 in Star Trek, according to "The Big Goodbye," but bowling thrives into the 23rd century?
Nimoy is terrific in this episode. No surprise there. He has good writing on his side, of course, but he brings a lot to the table. I love how Mr. Spock attempts to hold himself together by quoting multiplication tables. There's something very right about that: the logic of Math/Order trying to hold down the chaos of emotional distress. It doesn't work, but it's a noble attempt.
Finally, "The Naked Time" reveals another element of Star Trek that disappeared after this generation: the captain's undying love for his ship.
"Never lose you," Kirk says here, while under the influence. He's referring to the Enterprise, and talking about her like she's his lover. His passion for the ship borders on obsession. In the original series, the Enterprise was a main character, and a love for this particular ship by Kirk and others is an element that informed many of the best stories.
One might contrast this mad obsession with Captain Picard's blase, rote response at the destruction of the Enterprise D (paraphrased) in Generations: "I'm sure this won't be the last ship to carry the name Enterprise..."