Balance of Terror
In the episode, the USS Enterprise battles a Romulan ship after investigating an unidentified assailant that has methodically destroyed Federation outposts bordering the Neutral Zone.
The USS Enterprise, under the command of Captain Kirk, is investigating a loss of communications with a line of Earth outposts near the Romulan Neutral Zone, formed under the terms of the peace treaty that ended the Earth–Romulan War a century earlier.
The Enterprise races to Outpost 4's aid and contacts the base commander, Hansen, who reveals he is the only survivor of an attack by an unknown enemy.
Lieutenant Stiles, the navigator, a descendant of a service family that lost several members in the Earth–Romulan War, begins to question the loyalty of the Enterprise's first officer, Mr. Spock.
When the Romulan ship decloaks to launch a torpedo, Kirk tries to spring his trap, but a coolant leak in the phaser control room incapacitates Stiles and Tomlinson.
The Star Trek Compendium stated the episode was essentially a science fiction version of the submarine film The Enemy Below, depicting a cat-and-mouse game between the Enterprise as the American destroyer against a Romulan vessel as the U-boat.
On September 16, 2006, "Balance of Terror" became the first digitally remastered Star Trek episode, featuring enhanced and new visual effects, computer generated (CGI) spaceships, and high-definition format.
In 2016, The Washington Post ranked "Balance of Terror" the third-best episode of the entire Star Trek franchise, noting that it investigates the connection between wars and race, that it shows both sides of a conflict in deep space.
Critic Ed Gross praised the episode for exploring the theme of bigotry, and as "a piece of television that manages to conjure genuine suspense as one commander attempts to outmaneuvre the other".
[2] Guest star Mark Lenard, who portrayed the Romulan commander, returned in the episode "Journey to Babel" where he played Sarek, Spock's father.
Bryan Fuller called the episode a "favorite" and a "touchstone" which influenced the creation of the story arc in Star Trek: Discovery.
