A cloaked Romulan Bird-of-Prey destroyed Earth outposts along the Neutral Zone, and the Enterprise fought a tense duel that revealed what Romulans looked like for the first time.
In 2266 a Romulan Bird-of-Prey crossed the Neutral Zone set up after the Earth-Romulan War and destroyed several Earth outposts with a powerful plasma weapon while using an invisibility screen. The Enterprise was nearby, and Kirk interrupted a crew wedding to go to battle stations.
When the Enterprise intercepted the Romulans' transmissions, the crew saw for the first time that Romulans looked like Vulcans. Navigator Andrew Stiles, whose family had fought in the earlier war, openly distrusted Spock. Kirk and the Romulan commander, an experienced officer who privately disliked the war, fought a long game of hide and seek through a comet's tail and drifting debris.
The Enterprise finally crippled the Bird-of-Prey. The commander refused rescue and destroyed his own ship to keep its technology secret. Spock saved Stiles during the battle, though crewman Robert Tomlinson, the bridegroom, was killed. The incident showed the Federation that the Romulans had cloaking technology and were willing to test the treaty boundary.