Stardate 1709.2: A wedding between two crewmembers is interrupted when an Earth outpost along the Romulan border is attacked by an unidentified vessel. Kirk orders battlestations and the Enterprise races towards the Romulan Neutral Zone, an area separating the two powers which was established by subspace radio over 100 years ago, just as another outpost is destroyed. Kirk continues to try and identify the attacker, but Lieutenant Stiles, whose ancestors fought in the Romulan War, believes there isn't much doubt as to their identity. Sulu manages to pick up a visual image of a fleeing vessel and is able to track it despite an invisibility screen. Deciding to remain cautious until he can learn more about the attacker, Kirk orders the helmsman to shadow the vessel as it makes its way back to the Neutral Zone. The Romulans notice the Enterprise on its scanners but cannot determine if it's an enemy ship or a sensor echo. After holding a tactical meeting, and with some prodding from Stiles and Spock, Kirk decides that he must attack to prevent the enemy vessel from returning to its base and reporting Federation strength. After pounding the Romulan vessel with phaser fire, the Romulan commander de-cloaks and fires its plasma energy weapon and the Enterprise narrowly avoids destruction. Kirk pursues further and forces the Romulan ship into another exchange. A nuclear weapon is detonated and temporarily disables the Enterprise. Thinking the human vessel at his mercy, the Romulan commander moves in for the kill but falls into a trap. Despite a phaser coolant leak, the Enterprise heavily damages the Romulan vessel. Unwilling to surrender, the Romulan commander destroys his own ship.