The episode opens with Enterprise Captain Jean-Luc Picard dictating into his log that his ship is en route to a meeting where he will receive a briefing concerning the current situation along the border of the Cardassian / Federation demilitarized zone. Meanwhile, newly minted Lieutenant Ro Laren arrives in Ten-Forward to attend a welcome back party being given in honor of her return after recently graduating from Starfleet Advanced Tactical Training class.
The reunion is cut short when the Enterprise responds to a distress call from a Cardassian warship under attack by a number of small vessels identified as Maquis, a paramilitary organization of Federation citizens who have banded together and taken up arms against the Cardassians with whom they share the Demilitarized zone. When the raiders fail to respond as the Enterprise attempts to warn them off, Picard orders a spread of Photon torpedos detonated between the Cardassian and Maquis ships, causing them to break off their attack and withdraw. A number of Cardassian wounded are brought aboard the Enterprise for treatment, including the Captain of the Cardassian warship, Gul Evek. Evek warns Picard that unless the Federation tries harder to restrain the Maquis, the Cardassian military will be forced to take matters into their own hands.
Later the Enterprise has its rendezvous with Vice Admiral Alynna Nechayev's Excelsior-class ship and she informs Picard that Starfleet is very concerned about the Maquis, who have moved from a purely defensive posture to a more offensive one, their numbers expanding as they acquire more ships and weapons. She adds that Starfleet intelligence has learned that the Cardassians are continuing to surreptitiously supply arms to their citizens in the zone even though they had claimed to have stopped doing so, fueling fears that the Demilitarized zone âcould igniteâ. Nechayev sums up the briefing by telling Picard that without some kind of action against the Maquis, they could jeopardize the Federation / Cardassian peace treaty, resulting in the deaths of tens of thousands in a renewed conflict. She advises Picard that Starfleet has decided to infiltrate the Maquis hoping to find out more about their goals and plans, with the intention of eliminating the threat they pose. She completes the briefing with the revelation that the intelligence operative who Starfleet would like to use for the mission is already aboard the Enterprise.
Picard meets with the operative Starfleet has chosen, who is revealed to be Ro Laren. She is somewhat ambivalent about aiding the very same Cardassian government who killed so many of her people, including her father, during the Cardassian occupation of Bajor, her homeworld. Picard observes that her history of trouble within Starfleet and experience as a member of the Bajoran resistance fighting the Cardassians give her a certain âcredibilityâ. He also reassures her that in this particular instance the goals of the Federation and Cardassian governments happen to align, adding that assigning her to this important mission indicates Starfleet obviously has placed a great deal of faith in her.
Ro arrives in the DMZ and finds her way to a bar where she is contacted by members of the Maquis. After verifying her cover story, they quickly accept her into their ranks, although several of their number are concerned she may be a Federation spy and do not trust her. She immediately forms a bond with Macias, an elderly and paternal Bajoran who is the leader of the Maquis cell, who Ro obviously sees as a father figure. Macias tells Ro how he was beaten in his home in the zone by unknown assailants and nothing was done about it, the frequency of such incidents verify Maquisâ suspicions that the Cardassians scheme to run all the Federation citizens out of the DMZ with severe and harsh treatment, adding that all but the Maquis seem to be unaware of the Cardassian strategy. Soon after Ro joins the militants they hear rumors that the Cardassians are planning on arming their citizens in the zone with deadly Biogenic weapons. Alarmed by this news, the Maquis plan a preemptive strike to stop the Cardassian plot, however, Macias points out that they cannot mount such a strike without new stocks of medical supplies which they are critically short of. Ro offers to steal the needed supplies from the Enterprise, however, another Maquis, mistrustful of Ro and planning to monitor her, 'volunteers' to tag along.
Ro is lent a Maquis ship, and uses codes supplied by Starfleet intelligence for her clandestine mission to cross the sensor net at the DMZ border. She and the other Maquis operative next send a fake distress call to lure the Enterprise into a nebula which will hopefully help blind the Federation shipâs sensors. With her advanced tactical training skills, as well as some covert aid from the Enterprise, Ro is able to penetrate the Galaxy-class shipâs shields and beam away the medical supplies.
Returning to the Enterprise for a debriefing, Ro tells Picard of the Maquisâ strategy and Picard plots to manipulate the militantâs paranoia in order to set a trap for them, hopefully eliminating, or at least crippling, their organization. Ro is troubled by this, telling Picard that she has come to greatly admire and sympathize with the militants, especially since she was once a member of a resistance movement against the Cardassians herself. Nevertheless she tells Jean-Luc that she will reluctantly continue with the mission.
Returning to the DMZ, Ro is able to convince the Maquis leadership to plan an attack on the undercover convoy supposedly carrying the components for the biogenic weapon, though the convoy is actually a ruse to lure the militants into committing a large attack force which itself will be attacked and destroyed by a Federation fleet hiding in a nearby nebula.
Shortly before the planned strike is to take place, disguised Cardiassian militiamen attack the community which the Maquis cell is part of, and Macias is killed. As he dies, he tells Ro his death is not important as other Maquis like her will step forward to carry on the fight in his place.
Shortly thereafter a very unsettled Ro meets with Picard in the bar where she was originally recruited by the Maquis. She admits to Jean-Luc that sheâs having second thoughts about the mission, asking him to call it off, saying that the Maquis cell she belongs to isnât all that militant and may not even rise to the bait of the decoy convoy. Picard replies that her information contradicts everything his intelligence reports are telling him and that her foot-dragging isnât acceptable. He adds that if he finds out she has compromised the mission he wonât hesitate to have her court-martialed and sent back to the stockade. He decides to send the shipâs First officer Commander William Riker, back to the Maquis with her to keep an eye on her and assure nothing interferes with the mission.
The day for the operation against the supposed biogenic component convoy arrives, and as the Maquis fighters close in on it, Ro pulls a phaser on Riker, telling him she canât go through with the operation. She fires a low intensity particle beam into the Nebula, exposing the Federation attack force, and the Maquis ships break off their attack before they leave the DMZ, frustrating the Starfleet plan. With great regret, Ro tells Riker she feels she belongs with the Maquis more than she does Starfleet and beams away to another Maquis ship after asking Riker to apologize on her behalf to Picard.
Back on the Enterprise, Riker files his report with Picard in the captain's ready room, adding that Ro seemed very sure of her decision, her only seeming regret being that she had let Picard down. As Riker leaves, the camera pans to view a stone-faced Picard, obviously devastated by his protÃ©gÃ©âs betrayal of both himself and Starfleet.