The U.S.S. Enterprise is plagued by an outbreak of violent mood swings when it is visited by Sarek, the renowned Vulcan Ambassador.

Sarek, the renowned Vulcan Ambassador, is on a mission to establish relations between the Federation and a race of beings known as the Legaran. His arrival on the starship is preceded by his human Chief of Staff, Mendrossen, and a young Vulcan, Sakkath, the Ambassador's personal assistant. Mendrossen explains to Captain Picard that Sarek's age has recently caused him to tire easily, and asks him to dispense with the official ceremonies that would normally be accorded a visitor of Sarek's rank, so that he may rest. Picard is disappointed that Sarek will not be able to attend a concert arranged on his behalf, but defers to Mendrossen's wishes.

Picard later extends a personal invitation to attend the concert to Sarek's wife, Perrin, who thanks him and says that she will extend the invitation to her husband. When Picard departs, Perrin enters Sarek's room to find the Vulcan uncharacteristically annoyed by an apparent inability to meditate. Later in the evening, Sarek and his entourage attend the concert, where Picard is surprised to see the Ambassador, who is normally emotionally detached, moved to tears by the music.

During the course of Sarek's stay, sporadic bouts of anger and violence plague the crew of the U.S.S. Enterprise. Dr. Crusher is horrified when she is driven to strike Wesley, and seeks counsel from Troi, who expresses concern because it is just one of many similar incidents that have been reported to her. The situation becomes desperate when a brawl breaks out among the crew in Ten Forward.

Troi and Dr. Crusher theorize that Sarek is suffering from Bendii syndrome, a rare condition among Vulcans, characterized by a loss of emotional control. Although Mendrossen denies the suggestion, Sakkath, concerned about the success of the conference, admits that he has been attempting to telepathically reinforce Sarek's emotional control.

When Sarek is informed of the recent events, he so vehemently denies his affliction that it results in an outburst of anger, which proves Picard's point. Before the captain cancels the conference, he proposes that he and Sarek participate in a mind-meld in which they would become telepathically linked, and virtually share one mind. When Sarek agrees, Picard suffers through a whirlwind of the Ambassador's emotions unleashed in his mind, while Sarek is able to use the captain's strength to successfully negotiate with the Legaran delegates.

Cast:

Patrick Stewart as Jean-Luc Picard
Jonathan Frakes as William Thomas Riker
LeVar Burton as Geordi La Forge
Michael Dorn as Worf
Marina Sirtis as Deanna Troi
Gates McFadden as Beverly Crusher
Brent Spiner as Data
Wil Wheaton as Wesley Crusher

Guest Cast:

Colm Meaney as O'Brien
Joanna Miles as Perrin
Mark Lenard as Sarek
Rocco Sisto as Sakkath
William Denis as Mendrossen
John H. Francis as Science Crewman

Creative staff:

Director: Les Landau
Story By: Marc Cushman and Jake Jacobs
Teleplay By: Peter S. Beagle