K'Ehleyr, a half-human, half-Klingon ambassador, requests permission to come aboard the U.S.S. Enterprise to speak with Picard. Worf is noticeably agitated when the woman, his former mate, materializes accompanied by a young Klingon boy. K'Ehleyr tells Worf that the boy, Alexander, is their son. The Ambassador then informs Picard that she has come because K'Mpec, the dying Klingon leader, wishes to speak with him. Picard boards the Klingon ship, and K'Mpec requests his help in arbitrating the power struggle between his two potential successors. One of the contestants has been secretly poisoning him, and Picard must determine who is the murderer and prevent him from assuming K'Mpec's post. K'Mpec tells Picard that one of the contestants is Duras, whose deceit caused Worf's discommendation from the Klingon High Council.

Meanwhile, K'Mpec has died, and the rivals for the leadership of the High Council, Duras and Gowron, join Picard at his wake. There, Duras urges Picard to complete the rite of succession when suddenly, an explosion rocks the room.

Back on the U.S.S. Enterprise, Worf and K'Ehleyr share a tender moment, and Worf agrees to befriend Alexander. Meanwhile, Picard stalls for time by subjecting Duras and Gowron to an ancient ritual where they must prove their worthiness. Gowron later offers K'Ehleyr a bribe to influence Picard's decision, but she refuses.

The discovery that the bomb in the explosion was of Romulan origin leads the crew to suspect that one of the Klingon rivals plans to form an alliance with this Federation enemy. K'Ehleyr suspects Gowron because of the attempted bribe, but her suspicions turn to Duras when she finds evidence that proves Duras was involved in the conspiracy that led to Worf's discommendation, and that he somehow forced Worf to take the blame.

Dr. Crusher discovers that the bomb was implanted in the arm of one of Duras' men, while Duras attacks K'Ehleyr in her quarters. Worf rushes in, and K'Ehleyr gives him Duras' name before dying in his arms. An outraged Worf transports to Duras' ship. He attacks Duras, who reminds Worf that he is the only one who can clear his name. Worf kills him anyway, accepting his fate for the sake of vengeance. Returning to the starship, Worf informs Alexander that he will be cared for by Worf's adoptive human parents, and answering the boy's query, embraces him as his son.