First face-to-face encounter with the Romulans

For about a century after the Earth-Romulan War, the Romulan Star Empire stayed hidden behind the Neutral Zone set up by the peace treaty. The war had been fought entirely ship to ship, without visual contact, so no human had ever seen a Romulan. In 2266 that silence ended when outposts guarding the Zone were destroyed one after another.

The Enterprise, under Captain Kirk, identified the attacker as a Romulan Bird-of-Prey equipped with a cloaking device and a powerful plasma weapon. When the crew intercepted an image of its bridge, they discovered that Romulans looked almost exactly like Vulcans. The revelation stirred suspicion against Spock, notably from a navigator who had lost relatives in the old war. Kirk and the Romulan commander then fought a tense duel of patience and deception across the Neutral Zone.

Kirk prevailed, and the Romulan commander, refusing capture, destroyed his own ship after expressing respect for his opponent. The episode established the Romulans as one of Star Trek's major powers and introduced the idea, explored much later, that they shared a common ancestry with the Vulcans.