The highly regarded, but elderly, Ambassador Sarek, father of Spock, is ferried by the Enterprise on his final mission for the Federation. While aboard ship, the crew experiences an outbreak of irrational anger amongst themselves.
Federation Ambassador Sarek of Vulcan has arrived on board the Enterprise with his human wife, Perrin. His mission is to lay the foundation for trade relations between the Federation and the Legarans, after which time he will retire due to his old age. Though Captain Picard and his crew attempt to provide for Sarek and have arranged for a chamber music concert for him, the ambassador expresses apprehension and annoyance. Picard personally invites Perrin to the concert. Picard is surprised to find Sarek attending the concert with Perrin, and even more so when he starts crying in the middle of the performance, an emotional trait Vulcans normally suppress.
Across the ship, the crew starts to act uncharacteristically hostile to each other, including a large brawl in the Ten Forward lounge. The onset of the events is tied to Sarek's arrival. Ship's Counselor Troi and Chief Medical Officer Dr. Crusher believe Sarek may be suffering from Bendii syndrome, a degenerative neurological disease that only affects aged Vulcans, causing them to lose control of their emotions and emit "broadcast empathy" that destabilizes emotions of others around them. Picard attempts to approach Sarek about this, but Sarek's aides deny there are any problems. Picard asks Commander Data to speak with Sakkath, Sarek's second aide, who has mutual respect with Data; Data confirms that Sakkath has been attempting to channel his emotional strength into Sarek, but has been overwhelmed by the pressures of the conference. Picard directly confronts Sarek on the matter, who attempts to remain defiant of his problem. When Sarek breaks down emotionally in front of Picard, Picard realizes they may need to cancel the conference.
As Picard prepares to cancel with the Legarans, Perrin arrives and suggests an option: for Sarek to mind-meld with another as to temporarily transfer his emotions onto someone else; this would leave Sarek within his sense to successfully complete the conference and maintain his dignity, reputation and honor, but Perrin warns of the possible dangers to the receiver's mind from the strong emotions. Picard willingly agrees to be the host. Sarek performs the mind-meld with Picard, and is able to retain full control of his emotions for the duration of the conference. However, Picard, monitored closely by Dr. Crusher, suffers through the numerous emotions that Sarek has pent up for years, including his regrets of not being able to show his love of his wives Amanda or their son Spock, or his current wife Perrin. With the conference successfully completed, Sarek prepares to take his leave. Picard lets Perrin know of Sarek's love for her. Perrin says she has always known it. Sarek thanks Picard for his kindness, and with deep respect states "We will always retain the best part of the other, inside us."