K'Ehleyr informs Picard that the Klingon Empire is on the verge of civil war. The two factions that have divided the council for years are becoming openly hostile, because K'mpec, head of the council, is dying. The civil war is of the utmost importance, because Klingon wars have a habit of spreading-according to K'Ehleyr, eventually it'll bring in everybody, including the Federation. K'mpec is also on board the cruiser, and wants to talk to Picard, who beams over.
K'mpec tells Picard that he's been poisoned (and there's no antidote). He tells Picard that he must arbitrate the dispute over leadership of the Council (and hence, the Empire) after K'mpec is dead-and when Jean-Luc tries to decline, tells him both that to refuse would be a grave insult to all Klingons, and, more importantly, that it's too late: he's already given the order. K'mpec tells Picard that he's sure one of the factions' leaders poisoned him, and tells Picard to find out which it is-Gowron, an outsider, or Duras, the Klingon responsible for almost killing Picard and for Worf's accepting discommendation. Picard, of course, accepts-and then, scant seconds later, watches K'mpec die.
Meanwhile, Worf finds that Alexander knows nothing of Klingon ways (and doesn't even want to be a warrior), but when he confronts K'Ehleyr with this, she tells him that she is half-human, and that Alexander will choose his own way. She says she didn't tell him of the child last time she saw him because he would have insisted on the Oath, and she was not ready. When Worf cites his dishonor as a reason he cannot acknowledge Alexander, K'Ehleyr dismisses it as of no consequence, and demands to know what really happened in the Council chambers-after all, she knows Worf wouldn't just withdraw his challenge.
The two factions' ships arrive: the Vorn, carrying Duras; and the Barruc, carrying Gowron. Duras is contemptuous of Picard's being named to mediate, but has little choice but to agree to it. He insists, however, that Worf be kept off Klingon ships. In private, Worf insists that Duras cannot be allowed to lead the Council due to his father's treachery, and when he hears of K'mpec's poisoning, insists Duras must be responsible. Picard, while acknowledging Duras's past deeds and promising to keep Duras's deceptions in mind, tells Worf that he cannot hold Duras responsible for his father's crimes-and reminds Worf that he chose to accept the consequences of Duras's lie.
Just under an hour later, on K'mpec's ship, the Son-Che ceremony takes place, in which Gowron and Duras ascertain for themselves that K'mpec is truly dead (by prodding him with Klingon pain-sticks). Duras demands that the rite of succession be completed immediately, and when Picard balks, there's suddenly an explosion, which kills two Klingons and injures others.
Not long after, Worf talks to K'Ehleyr again. When pressed to reveal his feelings, he admits that he would have demanded the Oath-"but not just for tradition." She says she thought about telling him, but wasn't ready. Now, however, she's realized that she isn't complete without him either. They begin the Oath-but this time Worf cannot bring himself to complete it-for if nothing else, the sake of Alexander, who will be "another traitor from a family of traitors!" K'Ehleyr doesn't fully understand, but eventually respects Worf's decision-but she asks him "if you cannot be his father...at least be his friend."
Picard, who needs to delay in order to continue investigating both the explosion and the poisoning, asks K'Ehleyr how he can gain such time. When she mentions the old rites of succession, which take much longer than the modern ones, he decides to follow them. As she leaves, however, K'Ehleyr asks Picard about Worf's discommendation, since she knows he was there-Picard says he cannot discuss it.
Duras and Gowron are anxious to begin the ritual combat which decides the Council's leader, and nearly attack each other before Picard manages to impose order. They're not thrilled to hear that Picard is holding the Zha-Juc, in which both candidates must give verbal evidence about the battles they've served in, awards they've won, and so forth, to qualify for the leadership. However, they have no choice but to agree.
After we see Worf showing Alexander the batlekh, a weapon that's been in his family for ten generations, we see K'Ehleyr talking to Gowron. Gowron points out that she could accelerate the selection process, offers her anything she desires up to and including a Council seat, and when she refuses, implies that she'll end up as dead as K'mpec if she doesn't help.
Then, in Engineering, Riker hears Geordi and Data report on the explosion. The explosive was a triceron derivative, but that's unimportant. Of interest is that the bomb was only about three cubic millimeters in volume (and thus could have been hidden anywhere)-and more importantly, the detonator was triggered by molecular decay. And the only race that uses such detonators-is the Romulans.
In conference, it's agreed that one of the faction leaders must be working with the Romulans- which could significantly endanger the Federation. When K'Ehleyr, based on her conversation with Gowron, voices suspicions about him, Worf claims it must be Duras-and when K'Ehleyr asks why, Picard can say only that they've had indications in the past that he's untrustworthy. Due to the threat this poses to the Federation, Picard now insists Worf accompany him to the next gathering, despite the disruption it will cause.
As the Zha-Juc continues, K'Ehleyr begins researching the Enterprise's visit to the Klingon homeworld-accessing the ship's logs. The Zha- Juc is completed, and before declaring a short recess prior to the combat, Picard brings up the matter of the explosion, and brings Worf in. Worf's presence sparks massive outcries from both sides, and Duras threatens to bring the proceedings to a halt, giving in only when Picard tells him the only thing he can do now is forfeit his claim. Neither party is helpful, however, when Worf asks what their investigations have revealed, and neither claims anything was out of the ordinary. When the detonator is mentioned, both parties decide to return to their ship to confirm this.
During this, K'Ehleyr hooks into the Klingon information-net, and when she finds that all the Council records on the Khitomer massacre were sealed by Duras, calls up biographical information on him. Through an aide, Duras gets wind of this and confronts her. She accuses his father of treachery and him of covering it up, and says, "The son betrays his people to the Romulans, just like his father did-Duras..."
We see Riker and Dr. Crusher discover that one of the dead Klingons had the bomb implanted in his forearm-Duras's man. Then, Worf and Alexander enter K'Ehleyr's quarters-and find her alone, bloodied, and dying. Worf urgently summons a medical team, then hears K'Ehleyr say Duras was responsible. She takes Alexander's hand and places it on Worf's-then her hand slips away, and she dies. Worf howls in anguish, then goes through the Klingon death- ritual. When he sees that Alexander has never seen death before, he tells him "then look-and always remember."
When Dr. Crusher and a medic arrive, he leaves the child with them and heads for his quarters, where he takes off his sash and communicator, picks up the batlekh, and leaves. As Dr. Crusher, Picard and Riker watch as K'Ehleyr's body is taken away, they page Worf-and find he just beamed over to the Vorn. Riker begins assembling a team to get him back.
On the Vorn, Worf arrives and demands right of vengeance. When Duras claims that Worf, as a traitor, has no rights, Worf says that K'Ehleyr was his mate. Duras picks up the sword handed to him. We see Riker, Data, and a security guard enter the transporter room, phasers set to maximum stun-then we see the battle between the two Klingons. Duras tells Worf that only he can prove Worf's innocence, but Worf is beyond caring. Riker and the team arrive just in time to watch Worf defeat Duras and plunge the batlekh right into his breastbone. Duras dies-slowly.
The issue settled, all three Klingon ships leave. The Council is satisfied with the proceedings- Picard, however, is not. He harshly reminds Worf that despite the many races on board the Enterprise, all have agreed to serve Starfleet- and if they can't do that, they should resign. He is relieved, however, that Worf does not want to resign, and merely tells Worf that a reprimand will be put on his permanent record. When he asks Worf if there's any point in keeping silent about Duras's guilt any more, Worf points out that the members of the Council all participated in the lie as well-but one day, he says, he and his brother will "convince" them to speak the truth.
Finally, Worf tells Alexander that he will be sent to live with Worf's human parents, telling him that he needs a home and a family-something Worf cannot at present provide. In response to Alexander's question, he tells him, "Yes- I am your father," and embraces him.