Everyone who stands to lose from peace.
~ Valeris

The Khitomer Conspiracy were the primary antagonists of the movie Star Trek VI: The Undiscovered Country.

The seeds of the conspiracy were planted in the years leading up to the explosion of the Klingon moon Praxis in 2293, as various individuals in the United Federation of Planets, Klingon Empire, and the Romulan Star Empire opposed the thawing of relations between the Klingons and the Federation.

After the explosion of Praxis, these individuals worked to oppose peace negotiations between the Empire and the Federation, feeling that they would lose the most if the two powers set aside their differences so that the Federation could help the Klingons repair their homeworld.

Knowing that Valeris had been a protege of Spock, Federation Starfleet members of the conspiracy - which included Admiral Lance Cartwright, Colonel Patrick West, and Section 31 - had her assigned to the Enterprise under the command of Captain James T. Kirk, along with enlisted members Burke and Samno. The three of them carried out the assassination of Gorkon after the Klingon General Chang had his cloaked bird of prey fire on Gorkon's ship in a way that made it appear that the Enterprise had fired upon the ship.

However these acts did not derail the peace process as Chancellor Azetbur wanted it to continue. The group next tried to assassinate Federation President Ra-ghoratreii at the talks on the Khitomer colony. Kirk and his crew defeated General Chang over Khitomer, with Chang dying when his ship was destroyed. Kirk and his senior staff prevented the conspiracy from assassinating Ra-ghoratreii.

In the aftermath of the conspiracy Valeris and Cartwright were handed over to the Federation for trial, and both were sent to prison. Ambassador Nanclus was returned to Romulus and apparently executed by the Romulans not long after.

By 2298 Cartwright had died in prison. Valeris was believed to be the last known survivor of the conspiracy. However Klingon Intelligence learned that the Romulan who had been known as Nanclus had survived and had changed his identity before returning to the Tal-Shiar. A Klingon Intelligence operative assassinated this Romulan and the other Tal-Shiar section chiefs. For having helped Starfleet and the Empire avert a disastrous attack on Qo'noS, Valeris was freed and began a new life as the civilian pilot T'Leris.