A secret alliance of Starfleet officers, Klingons and a Romulan ambassador who murdered Chancellor Gorkon and tried to kill the Federation President to prevent peace between their powers.
The Khitomer conspiracy is the cabal exposed in Star Trek VI: The Undiscovered Country. After the explosion of Praxis forces the Klingon Empire to seek peace, hardliners on every side join forces to keep the old hostility alive.
Its members include Admiral Cartwright and Colonel West of Starfleet, the Klingon General Chang, the Romulan ambassador Nanclus and Lieutenant Valeris, Spock's protégée aboard the Enterprise. Using a Bird-of-Prey that can fire while cloaked, they make it appear that the Enterprise attacked Gorkon's ship, and two crewmen beam over to kill him. Kirk and McCoy are convicted and sent to Rura Penthe.
Spock draws the names from Valeris by mind meld. The Enterprise and Excelsior destroy Chang's ship above Khitomer, and the assassin at the conference is stopped in time.