That evening, as Worf and Alexander prepare to leave, however, they are set upon by a band of assassins. As Alexander seeks cover, Worf tries to fight them off, and succeeds with the help of a Klingon watching from the shadows. The other Klingon congratulates Worf, and announces himself as K'mtar. "Your brother sent me here to protect you."
K'mtar is an advisor to Worf's House, so trusted that he is considered family - and he is very concerned by the assassination attempt. A dagger left behind by one of the assassins bears markings of the Duras family, and K'mtar says other evidence links Lursa and B'Etor to the crime. The hunt for the sisters begins, with K'mtar very skeptical of the Enterprise's ability to find them. Shortly thereafter, K'mtar also persuades Worf to help him convince Alexander to become a warrior, as one day Alexander will be forced to lead the House, and must be prepared. Worf agrees, and K'mtar begins by telling Alexander that if he were a warrior, he'd be able to protect his father, as he was unable to do that day during the attack.
Through a conversation with Quark, Riker hears that the Duras sisters are trying to get some illegal mining done in the Colla system, and the Enterprise heads there post-haste. (K'mtar, however, seems somewhat nonplussed.) While the ship is en route, however, Worf, Alexander, and K'mtar work on honing Alexander's fighting skills by recreating the assassination attempt. Alexander handles himself well, but then refuses to kill his holo-opponent, sparking a major outcry from K'mtar.
The Enterprise reaches Colla Three, and in a mine-shaft find Gorta, a miner abandoned by the sisters. In exchange for passage off-world, he tells them that they are heading to the Ufandi system to sell the ore to a Yridian trader. Later that day, K'mtar apologizes to Worf for his earlier outburst in the holodeck, but insists that Alexander must be convinced to become a warrior. He suggests sending Alexander to a Klingon academy off the ship, and threatens to invoke ya'nora kor (questioning Worf's fitness as a parent) to ensure it. He tells Worf to stop thinking of himself: "it is Alexander we should be considering." However, neither Worf nor Alexander is willing to consider this option, and Alexander in particular feels betrayed by the insistence, believing that K'mtar is "just like my father ... leave me alone!"
The Enterprise locates the Duras sisters through a bit of trickery with the Yridian traitor, and opens communications with them. While they are unrepentant in their actions, they deny all responsibility for and all knowledge of the assassination attempt. Riker invites them over to talk, and they accept.
On board, they dismiss the dagger as a plant meant to embarrass them, and K'mtar leaves to call Kurn. Just after he does so, however, Lursa and B'Etor notice another symbol on the dagger's hilt: one representing Lursa's son. The only trouble is, Lursa has no son - yet, although she recently became pregnant. "Where did this come from?"
Worf, intending to find out, goes to find K'mtar, only to stop him moments away from killing Alexander with a disruptor. Worf is prepared to kill K'mtar, but suddenly hears him say that he is Alexander!
Alexander, that is, from forty years in the future - and he convinces Worf of his identity by correctly recounting what happened when K'Ehleyr died. He came back with the aid of a man he met to change the past - because without that change, Alexander knows he was/will be responsible for Worf's murder. Alexander explains that he never became a warrior, but instead became a diplomat, and that his interest in peace was perceived as a weakness by the other Great Houses, sparking Worf's assassination on the floor of the Council chamber.
Worf is not convinced that all is lost, however - he realizes that with time now disrupted, anything can happen, and also assures "K'mtar" that things have changed - although Alexander's opinions haven't altered, Worf's have. Worf now realizes that Alexander must "choose his own destiny ... and I believe it will be a great one." K'mtar embraces Worf as a son would a father, and then departs.
The next day, Worf finds Alexander in the holodeck, practicing his fighting skills. He tells Alexander that K'mtar had to leave, but that K'mtar will continue to care for him no matter what he chooses to do with his life - and that "there will be plenty of time for practice." Alexander puts down his bat'lekh, and the two leave the holodeck together.