The episode begins with the Enterprise en route to Qo'noS so that Picard can attend the installation of Gowron as Leader of the Klingon High Council (see: "Reunion"). Unexpectedly, the Enterprise is intercepted by a Klingon vessel, the Bortas, which is to escort the Enterprise to its destination. Commanding the escort vessel is Gowron, who informs Picard of a conflict â one that could throw the Klingon Empire into a civil war â between himself and the House of Duras for the position of Leader of the High Council.
In a bid to restore his family honor Worf requests a leave of absence which Picard grants. He seeks out his brother Kurn who is Captain of a Bird-of-Prey. Kurn tells Worf he opposes Gowron and has the support of several squadron commanders within the Klingon fleet. In addition he informs Worf that most of the fleet has not yet chosen a banner to follow, be it either Gowron or the House of Duras. However Worf convinces him that remaining with Gowron is the best chance to restore their family honor. Kurn reluctantly agrees but must speak to his allies.
As Gowron is about to be installed as Leader of the Klingon High Council the Duras sisters interrupt with a challenge. With them is Duras' illegitimate son Toral who has the lineage necessary to challenge Gowron's leadership. The council votes to accept the challenge and assigns the position of "Arbiter of Succession" to Picard; because he must be neutral in order to interpret the law and see that the rightful person acquires the position. After the sisters meet with a Romulan officer and a mysterious woman, they invite Picard to their home to assure him choosing Toral would be in the Federation's best interest. Picard is suspicious of possible motives and alliances the Duras sisters made and the next day rejects Toral as a candidate at the High Council, stating that there is no precedent in Klingon law for allowing an inexperienced young person to assume leadership. However, many Council members indicate their support for Toral's challenge.
Worf meets with Gowron on the IKS Bortas and offers the support of several Klingon warship squadrons (led by Kurn) to Gowron in exchange for restoring his family's honor. Gowron rejects the offer saying it is not enough. Instead he attempts to enlist Worf's aid in acquiring Starfleet assistance but Worf rejects the idea; he's already been warned by Picard that the Federation cannot be further involved. At that moment the Bortas is attacked by two Birds-of-Prey. The ship suffers heavy damage, including the loss of their weapons and warp-drive. Gowron orders the transmission of a distress call requesting assistance from any loyal ships. On the Enterprise the crew pick up the distress call but when Riker questions Picard's decision not to intervene he counters that if they go to the aid of the Bortas they will be dragging the Federation into a Klingon civil war. He then orders the ship out of the combat area.
On the Bortas, Worf manages to get the ship's disruptors online. But instead of opening fire they try to lure the attacking ships in, knowing that they will try to board and finish off the crew. Sure enough the Birds-of-Prey drop their shields to allow transport and Worf opens fire, obliterating one of the attacking ships. However when he fires on the second ship the disruptor blast impacts on the ship's shields. The remaining Bird-of-Prey then returns fire knocking the Bortas' weapons offline and causing life support to fail. Just as all seems lost another Bird-of-Prey arrives and fires on the first forcing it to flee. The arriving ship is revealed to be Kurn's who, along with his crew, has "come to defend the Empire and follow the banner of Gowron."
With the fighting over, temporarily, the Enterprise returns to Qo'noS and Picard completes the rite of succession installing Gowron as Leader of the High Council. As a mark of thanks for their actions Gowron restores Worf's family honor. Back on the Enterprise Gowron informs Picard that the Duras sisters are assembling a fleet and, along with Worf, asks for Federation assistance in fighting these "enemies of the empire". Riker points out that these "enemies" are Klingons but Gowron counters that by right and tradition he is the sole leader and that all who oppose him are traitors. Picard reiterates that the Federation cannot get involved in Klingon internal affairs and must therefore decline Gowron's request. This leaves Worf in the difficult position of choosing between Starfleet or returning to help his people. Worf resigns his Starfleet commission to join the Klingon Fleet as civil war threatens to unravel the Klingon Empire.
Back at the home of the Duras sisters, the Romulan officer Movar announces that Picard has rejected Gowron's plea for help. When Toral triumphantly declares Picard as a coward, he is silenced by the female Romulan. Stepping out into the light, the Romulan Sela (Unification Part I and Unification Part II) declares to everyone, "we should not discount Jean-Luc Picard just yet. He is human and humans have a way of showing up when you least expect them."