Written by Paul Schneider and Gene Roddenberry
Directed by Vincent McEveety
Every now and then, the original Star Trek series got things just about perfect. This means a variety of things came together so well that it stands the test of time and holds up as well watching it now as it did forty years ago. Such is the case with Balance of Terror. It introduced the Romulans as enemies of the Federation, as well as setting the stage for the ancestral link to the Vulcans. This is only alluded to in this episode and not confirmed.
There’s a wedding between Spec. Angela Martine and Spec. Robert Tomlinson (portrayed by Barbara Baldavin and Stephen Mines) takes place on board the Enterprise as it’s patrolling an area of space where Earth Outposts exist along the Neutral Zone . This zone was established after a war with the Romulans when neither side laid eyes on the other. A breach of this Neutral Zone by either side would mean an act of war. The wedding is interrupted by a distress call from Outpost 4.
Outpost 2 and 3 are gone. Not only are they gone, but the asteroids they were constructed on have been pounded to bits. When the Enterprise makes contact with Outpost 4, they learn that Outpost 8 is also gone. Outpost 4 is without a deflector shield from the attack on them by an unknown vessel with an unknown weapon.
The Enterprise gets a visual from Outpost 4 just before it’s destroyed as well. What they see is a ship they have never seen before emitting a burst of energy that destroys the unprotected Outpost.
One of the crew, Lt. Andrew Stiles, (portrayed by Paul Comi) has a family that was killed in the earlier war with the Romulans. When the Enterprise manages to patch into the visual communication from the bridge of the Romulan vessel, the crew sees the Romulans for the first time. The Romulans greatly resemble the Vulcans, sparking prejudice in Stiles against Mr. Spock (Leonard Nimoy).
Captain Kirk (William Shatner) has the Enterprise shadow the cloaked Romulan vessel, hoping to convince them there’s an echo in space behind them. What follows is a strategic battle between the Romulan Commander and Kirk as the two attempt to out-maneuver each other. Kirk must deal with the Romulans before they re-enter the Neutral Zone to prevent their being able to claim the Enterprise fired upon them first.
The story here seems largely borrowed from a variety of sources, including the movie The Enemy Below and one of Forester’s Horatio Hornblower stories. It could be argued that so many stories of battle and strategy seem the same, and yet there’s no official attribute anywhere.
Mark Lenard makes his first appearance here, not as Spock’s father, the role he would be most remembered for in Trek, but as the aging Romulan commander. He comes off as tired of the battle, but loyal and dutiful to those he takes orders from. His performance conveys this, as he is diligent and conscientious, but also tired and sometimes lethargic. His performance goes a long way to make the story convincing and it’s no wonder he was brought back for future work and what would be an ongoing character through the movies and into Star Trek: The Next Generation.
Shatner benefits too from not being totally full of himself. He’s not all-knowing and invincible here and that works for Kirk. He’s confident and decisive, the way the Captain should be, but he doesn’t come off as God-like.
Slight Spoiler
The weakest part of the story is the prejudice against Spock by his crewmate and how that’s resolved. In the end, Stiles and Tomlinson are in danger and Spock rescues Stiles, allowing Tomlinson to die. Stiles is amazed that Spock saved him and didn’t let him die. I really don’t understand that way of thinking – someone else had to die. Would having Spock rescue Tomlinson first have made a case that he had some bias? What if Tomlinson was simply closer to the door and a quick, easier rescue than Stiles? What if Spock made the decision that Tomlinson had more to live for since it was his wedding day?
End Spoiler
There is some terrific backstory here given about the history of the war between Earth and the Romulus – that it was fought in primitive vessels with nuclear weaponry. It’s something that isn’t brought up again that I could remember and it was surprising to hear.
The effects are typical 1960s effects. They aren’t horrible by any means, just look like they are primitive by post-Star Wars standards. Nowadays shows have a “bible” which allows them some consistency. That wasn’t done back then and some people might pick up on the fact that some of the effects in Balance of Terror is shown as being associated with other weaponry later on in the series.
That said, the story of the stand-off between the Romulan Commander and Kirk makes the episode one of the best of the original series. It’s definitely an episode to show people who aren’t familiar with the show. Other than the weakness of the story involving Stiles and Spock, it’s perfect.

Previous episode in the series (link): Star Trek: The Original Series – The Conscience of the King
Next episode in the series (link): Star Trek: The Original Series – Shore Leave
I watched The Enemy Below in the 1970s, when local independent stations filled their air time with older movies and home video was a “thing” only for the very wealthy. I wasn’t a Star Trek fan, but I was a WWII movie fan, so I’d watch this whenever Miami’s WCIX-TV had it in the rotation (usually as a weeknight 8 PM Movie offering).
Years later, after I FINALLY got into Star Trek after watching the first feature film, I watched Balance of Terror and couldn’t help thinking that the second half seemed vaguely familiar. I couldn’t pinpoint it exactly, but it did remind me of The Enemy Below, although the writers, Paul Schneider and Gene Roddenberry, do a good job of adding enough original material (like the interrupted wedding and Stiles’ latent bigotry) to make that story their own.
There was a lot of borrowing material back in the day. The difference was they didn’t have the internet with people going “hey, wait a minute..”
Borrowing is still done, in literature, music, and movies. It’s a perfectly acceptable technique; Star Wars is one of the great borrowers (especially in the old EU/Legends novels), but the movies borrow liberally from other films. The trick in doing that is figuring out the difference between taking certain ideas from other sources and outright, blatant plagiarism. Back in Star Trek’s day (per that book I recommended a few weeks back), lots of people knew Balance of Terror was really The Enemy Below.
There are, I’ve been told, only seven major stories that can be told. Everything else is merely riffs on those stories.
The Internet certainly would have had a lot of folks saying “Hey, bro, isn’t that really The Enemy Below…in space?”
Re borrowing, The new movie I’m working on will have DNA from various films. Mostly subliminal ones, though I am sure that keen film buffs will spot many of them.