Balance Of Terror
“Balance of Terror,” inspired by submarine warfare, sees the Enterprise come up against old enemies of Earth, the Romulans – the first time the classic Trek race appeared in the series – and engage in a fierce battle that leaves both vessels marooned in space. As our perspective veers between Kirk and the Romulan commander (Mark Lenard’s other important Trek role), we see the similarities between the two foes rather than their differences.
Later episodes would help flesh out the Romulans even more, but this one introduces the intriguing idea that they’re the belligerent cousins of the Vulcans, which leads to Spock taking abuse by members of the crew who equate his kind with their enemies. This plot thread serves as a reminder that, even in the enlightened times of Starfleet, xenophobia and racism sadly still exist in moments of high tension.
As has become obvious through our rundown of TOS‘s best episodes, a unifying theme of the show was its attempt to champion peace over the needless conflict of war and “Balance of Terror,” which smartly captures the futile hostility between two races, is perhaps the finest example of Trek‘s most noble theme.