Although Picard refuses to involve Starfleet in Klingon affairs he fears the Romulans will try to take advantage of the situation, citing history of previous collaboration between the Romulans and the House of Duras. He sums up the situation to Fleet Admiral Shanthi saying the Romulans are prepared to take enormous risks to gain any advantage over the Federation - "can we seriously expect that with the future of the Klingon Empire in the balance they are content to just sit back and watch?"
After convincing Starfleet of the threat and devising a way to detect cloaked Romulan ships, Picard is put in charge of a fleet which will create a blockade along the Klingon-Romulan border against Romulan convoys supplying the Duras family. Because of a manpower shortage amongst the ships available, various Enterprise officers must be put in temporary positions on key ships to coordinate fleet preparations and deployment; Riker and La Forge are assigned as temporary captain and first officer of the USS Excalibur. Data asks Picard why he was not selected to command one of the ships. After all, the android points out, he is the third most senior officer among the Enterprise staff (and, given his twenty-six years in service, probably the most experienced officer on board save Picard himself). Somewhat reluctantly, Picard gives Data his own command, the USS Sutherland. The fleet is then quickly dispatched to the Romulan-Klingon border.
On the Sutherland, Data is confronted with the prejudice of his crew which is voiced by his executive officer, Commander Christopher Hobson. They are not confident an artificial life-form can be a commanding officer. Data notes his objections but denies Hobson's request for a transfer.
Meanwhile the Duras sisters meet again with Commander Sela who looks very similar to the late Starfleet officer Tasha Yar; but the sisters are troubled by the possible interference of Picard's fleet in their plans to take over the Empire. Sela sends word back to Romulus for all available ships to be at the border in 2 days. Meanwhile, following heavy combat, Worf, Kurn and the crew of Kurn's ship are resting, Klingon-style, while their ship is repaired. This consists of mostly drinking and fighting. However the capital city is deemed neutral ground so when Worf has an encounter with a Commander from the Duras fleet who has insulted him, Kurn prevents him from starting anything citing, "Larg's men are all around us, as are mine." Later following an argument with Kurn in which he storms off, Worf is attacked and abducted from the 'establishment' by unknown attackers.
With the Federation fleet in position on the Klingon-Romulan border, a detection network is established between the ships to uncover any cloaked Romulan convoys supplying Duras. Commander Sela orders her scientists to work on a way to disable the network, but to confuse Picard she contacts the Enterprise and reveals her identity as she warns the fleet to withdraw. Initially concluding Sela's existence is a Romulan trick Picard is visited by Guinan who tells him Sela is not only telling the truth, but that he was somehow responsible for her conception by sending Tasha on the Enterprise-C 23 years in the past despite her death on the Enterprise-D years ago.
To get to the bottom of things Picard invites Sela to a meeting on the Enterprise, to which she agrees. Once on board Picard avoids Sela's questions and asks about her background. Sela quickly deduces that what Picard really wants to know is how she is the daughter of Tasha Yar. Her story corroborates Guinan's recollection and Picard concludes that, however strange, Sela is indeed Tasha's daughter. Without making any headway with Picard, Sela gives him a fourteen-hour deadline to either retreat or be attacked.
At the same time, Worf's kidnappers deliver him to the Duras sisters, who try to bribe Worf to join them by marrying the young attractive B'Etor and be the power behind Toral in the High Council. Worf rejects their offer since their methods and cooperation with the Romulans is without honor. Sela overhearing Worf's decision orders him taken away for "questioning", promising to return him later.
Picard becomes concerned that as time passes and the deadline nears the fleet may have to square off against the Romulans which could very well widen the war. He contacts Gowron and asks that he launch a full offensive on the Duras fleet; forcing the sisters to call for help and the Romulan convoy to take action.
On Sela's Warbird word comes in of Gowron's all out assault and that the Duras are running low on supplies and nearing defeat. On the plus side the Romulans believe they have a way to disrupt the Starfleet detection grid. Suddenly they note that one of Picard's ships is withdrawing from the blockade, apparently suffering problems with their warp drive. This opens a hole in the network but Sela suspects it's too good to be true, and instead decides to disrupt the network. A beam aimed at one of the ships should disable the detection grid in a localized area, and Sela chooses Data's ship to be the target. How she knows he is commanding one of the ships and which one it is is never explained.
The Romulans use the beam and the network begins to fail around the Sutherland. Picard orders the fleet to retreat and redeploy the grid further into Klingon space but Data, after doing some quick research, orders his ship to stay behind. Data theorises that the beam used by the Romulans may have made their own ships detectable. On the Enterprise, Chief O'Brien, who is serving at Tactical, notes that the Sutherland is not withdrawing with the rest of the fleet. Picard orders Data to explain why he isn't complying with the retreat order but Data replies asking Picard to 'stand by'. After scanning the area around their ship, several anomalies are detected. Data orders low yield photon torpedoes fired at the anomalies but Hobson protests stating they have no idea what they are and that even if they are Warbirds, the low yield torpedoes won't do any damage. Data responds with a calculated expression of anger to force his compliance.
The photons uncover three cloaked Romulan ships and Sela, realising the game is up, orders a retreat. Without the convoy the Duras are losing quickly to Gowron's attack. Worf is returned to the Duras sisters but B'Etor rejects him, and just as Worf is to be executed the room they are in is hit by weapons fire. Worf seizes the opportunity and attacks his Romulan guard. Seeing that Worf is about to emerge victorious the sisters escape via transporter, leaving Toral behind. Kurn and several warriors arrive and take Toral into custody with Kurn sneering to Toral that "Gowron is looking forward to meeting you".
With the civil war ended, Picard orders the rest of the fleet to return to Federation space while they return to Qo'noS. Data reports to Picard in his ready room, telling the captain he is prepared to be punished for disobeying a direct order; he does not believe it ethical to defend himself by saying that the ends justify the means. Picard responds that Starfleet wants officers who can think and act independently, implicitly admitting that he was wrong for not giving Data his own command earlier. He dismisses Data with a smile and a "Nicely done!"
In the High Council chambers, Picard gives Gowron a debriefing and data on the encounter with the Romulans. With Gowron's position on the High Council secure, he thanks Picard and rewards Worf with Toral's life. Worf is given the honor of killing the son of the Duras family, which disgraced his family and sent Worf into exile to cover up Duras' betrayal of the settlers at Khitomer. (see: "Sins of the Father") Realizing it does not agree with his personal philosophy, and reflecting on the numerous disagreements he had on the "Klingon way", Worf spares Toral's life and requests permission to return to the Enterprise. Picard happily accepts and Worf's brother Kurn is left in the High Council to rebuild the family honor.