Kirk and the Enterprise encounter a Romulan ship near the neutral zone.
This is one of the most enjoyable episodes of the original series with a great plot, fantastic character moments and a number of memorable performances.
I have seen Balance of Terror several times and it never fails to grip me. As others have referenced, it is based on the 1957 war film 'The Enemy Below' and wonderfully applied within the Start Trek universe. The tension created throughout the tactical battle between Kirk and the Romulan Commander is some of the best in the franchise.
Written during the sixties, it is full of highly relevant themes of the era, such as the Cold War tensions between two opposing superpowers and the personnel serving at the front lines. Particular emphasis is placed on the role of command and the pressure of decisions that could provoke conflict. Racial tensions and xenophobia are also in focus in some of the most emotive scenes.
Several of Star Trek's most memorable character moments are seen in this episode from both regular and guest characters. Spock, Bones and Lt. Stiles have strong moments of dialogue, antagonism and heroic action, whilst Kirk is the tower of strength holding it all together. On board the Romulan vessel Decius and the Centurion are equally compelling with their Commander brilliantly mirroring the same strengths as Kirk.
All cast performances are excellent, but William Shatner and Mark Lenard command the screen as much as their ships and crew.
For me it is one of the greatest Star Trek episodes and if it was a more original story I would consider it a perfect episode of television. I rate it as a 9.5/10, but I round upwards.
