The Romulan Star Empire — a mysterious former nemesis of Earth unheard from for a century — returns and destroys several border outposts with a mysterious and super-scary weapon. The Enterprise responds and has protracted battle sequences (think submarine warfare … in space!) before Kirk’s tactical genius bests Spock’s dad — err, the Romulan commander (Mark Lenard) — and destroys the invading ship preventing another war and cementing our boy Jimmy as, well, our boy Jimmy. He’s apparently of a kind. And a sorcerer!

Why it’s important

“Balance of Terror” introduces one of Trek’s main villains, the Romulans, and does so in a way that is amazingly consistent with what we see of them for the next 40 years — unlike, say, the Ferengi, who go from allegedly eating their enemies to caterers and bartenders in six years flat. Of course, the episode also has the big reveal that the Romulans are offshoots of the Vulcans and introduces the concept of the cloaking device to Star Trek. It’s an extremely foundational hour of the franchise. Just think if that racist dude Stiles (Paul Comi), the Enterprise’s navigator in this episode whose ancestors fought and died in the previous conflict with the Romulans, had stuck around!

What doesn’t hold up well

The previous conflict with the Romulans as stated by Spock and others, is too Earth-centric even for first-season TOS standards — and especially if you consider the events of “Star Trek: Enterprise” (but even if you don’t). Apparently, Earth’s war with the Romulans occurred after the coalition that would become the Federation was established in Enterprise’s final episode “These Are the Voyages …” but before the Federation itself was formed. Or something.

Dramatically, it’s interesting in “Balance of Terror” that the Romulans have never been seen by humans (and it sets up the Big Moment™ when Spock sees a dude who looks just like his pops on the viewscreen — even though we don’t see Mark Lenard playing Sarek until season two). But it’s hard to believe that no visual communication or prisoner taking was previously possible, based on the 22nd-century technology on “Enterprise,” to say nothing of the visual communications technology available in the real world in the 21st century. It’s too bad that Spock didn’t just say that the Romulans refused visual communication back in the day. That would have been more believable than the apparent lack of Skype on Romulus or Earth 150 years from now. Maybe the Romulans were just way into Snapchat?

“Enterprise” also later pisses all over the wonderment of the cloaking device by giving Jonathan Archer’s crew’s a clear understanding of the technology and knowledge that the Romulans (and others) use it. “Selective bending of light,” indeed, Mr. Science Officer.

Lastly, the bad science of TOS pops up by asserting that the Romulans are a real threat despite their vessel’s lack of warp drive. Maybe Romulans have warp (even though the Bird of Prey seen in this episode doesn’t) making the Romulans a threat to the Federation in a larger sense, as opposed to being on par with the goofy aliens from TNG’s “The Outrageous Okona.” But the cat-and-mouse game is undercut by the fact that the Enterprise should be able to outrun the Romulan vessel several times over.

Final thoughts

Complaints aside, it’s possible that this episode set up the very idea of recurring villains in Star Trek, a huge, huge deal. Soon after, the Klingons were introduced, and the two main rivals of TOS were set (with all due respect to a certain dude in a certain rubber lizard suit and Harcourt Fenton Mudd). Beyond that, “Balance of Terror” is fascinating because it’s willing to show actual bigotry (from a 23rd-century human!) as a way to show why bigotry is wrong and something humanity was still working to move past (and mostly succeeding). It’s very effective, but it’s also unusual for Trek and would have been unheard of in TNG, when all humans were apparently beyond such things.