Worf is concerned that his son Alexander isn't pursuing his Klingon heritage. Alexander has reached the age at which he should declare his desire to become a Klingon warrior. However, Worf is appalled to learn Alexander has no such intention.
While awaiting a rendezvous with the USS Kearsarge near the Vodrey Nebula, after listening to Worf's complaints about Alexander's rebellious attitude, Captain Picard suggests Worf should expose Alexander to more of his heritage.
The Enterprise stops at Maranga IV so the father and son can go to a Klingon festival. The exposure to Klingon culture goes well for a time. However, while there, the two are confronted by a trio of Klingon thugs. Before the assailants can mount an attack, a Klingon named K'mtar arrives and fights them off. K'mtar reveals that he is a distant relative who has come to protect Alexander. K'mtar accompanies Worf and Alexander back to the ship, where the two quickly bond. Learning of Alexander's quandary, K'mtar assures the boy of the value of becoming a warrior.
K'mtar agrees to help with Alexander's training. But when his initial attempts at teaching yields little results, he recommends to Worf that Alexander be sent away for training at a Klingon military academy. When Worf expresses reluctance at pursuing this course, K'mtar threatens to invoke Klingon law and take custody of Alexander away from Worf.
Worf and K'mtar bicker until Alexander reminds them tartly that he is part-human on his mother's side. Both Worf and K'mtar quickly rebuff his statement, insisting that Alexander fully embrace the Klingon way of life. However, they cannot agree on who should finish raising Alexander. Worf is furious when K'mtar implies that he is a bad father and hotly fires back implications that K'mtar is a meddling busybody.
Meanwhile, the Enterprise crew is attempting to find out who attacked Worf and Alexander on Maranga IV. A dagger left behind had a mark from the House of Duras, and following this lead Riker and the crew contact Deep Space Nine and speak with Quark, from Star Trek: Deep Space Nine, which was on at the same time. Using information given by him, the crew locates the Duras sisters and accuse them of trying to assassinate Worf, which they deny vehemently. When the dagger is presented as evidence, the sisters make a disturbing discovery... Several markings on the knife denote family members, including one for Lursa's son, even though Lursa herself only recently learned she was pregnant.
Meanwhile, Worf discovers K'mtar in Alexander's room, preparing to kill the boy. Worf attacks K'mtar and immobilizes him. He confesses that he was behind the attack, which he used to gain their trust. Furthermore, he reveals that he is in fact Alexander – from the future year 2410– and he has come back in time to try to prevent Worf's murder.
The future Alexander had blamed himself for having allowed Worf to die, since he had never chosen the life of a Klingon warrior. Worf immediately realizes that K'mtar is in fact his adult son, and Worf tells him that he can only die happy if he knows he allowed Alexander to chart his own course. K'mtar then returns to his own time. Worf determines to approach his young son with a new attitude in the future.