A Romulan scout ship, under attack from a pursuing Romulan Warbird, comes charging across the Neutral Zone. Its sole occupant, Setal (James Sloyan), desperately requests asylum, which the Enterprise grants. Setal claims that a secret Romulan base along the Neutral Zone is the site of a massive Romulan fleet poised for an invasion.
Ron Moore's second TNG script is a marked improvement over his first. "Defector" documents — with high stakes and no shortage of fascinating twists and turns — a consistently interesting battle of wits between the Romulans and Federation. In its third season, TNG has turned the Romulan Empire into a worthy nemesis that is as sneaky and cunning as it is aggressive and threatening.
The central question of this story is whether Setal is actually telling the truth, or if he is a Romulan spy trying to lure the Enterprise with false intelligence into illegally entering the Neutral Zone and starting a war. Setal is perfectly played by James Sloyan, who conveys the urgent sincerity of a man trying to prevent a war while at the same time playing a man who is still every bit Romulan at heart, from his love for his homeland to his hatred of the Klingons (he curses Worf in an early scene) to his acerbic, superior attitude. He's here because he wants to stop what he believes is a misguided offensive that will destroy his homeland, not because he wants to betray it. The plot thickens when Setal is revealed to actually be Admiral Jarok, a high-ranking official responsible for infamous attacks on the Federation.
Picard's dilemma is that he has no evidence of a Romulan invasion plot other than Jarok's word. Indeed, evidence suggests that the Romulans' pursuit of Jarok might have been staged entirely for the Enterprise's benefit. In a startlingly terrific scene, Picard pointedly gives Jarok a wake-up call, telling him that he's already a traitor to his people, no matter how much he may think he's trying to be a patriot, and that he should follow through on his intentions and give the Enterprise the information they need to investigate the allegation properly.
It all leads to a dangerous venture into the Neutral Zone, which leads to another interesting showdown with Tomalak. The Romulans' willingness to use Jarok as a patsy in this plan is diabolically devious — one might say cruel — and makes Jarok the tragic figure in a heartless chess game. Just when the Enterprise looks outmatched and outgunned, Picard has one last trick up his sleeve. The writers had cleverly sneaked in the crucial clue (about the cloaked Klingon escorts) just under the radar. This chess game ends in a stalemate that keeps war at bay.