Plot

On the eve of retirement, Kirk and McCoy are charged with assassinating the Klingon High Chancellor and imprisoned. The Enterprise crew must help them escape to thwart a conspiracy aimed at sabotaging the last best hope for peace.

After an explosion on their moon, the Klingons have an estimated 50 years before their ozone layer is completely depleted, and they all die. They have only one choice - to make peace with the Federation, which will mean an end to 70 years of conflict. Captain James T. Kirk and crew are called upon to help in the negotiations because of their experience with the Klingons. Peace talks don't quite proceed, and Kirk and McCoy are convicted of assassinating the Klingon High Chancellor, and imprisoned on Rura Penthe, a snowy hard-labor prison camp. Will they manage to escape? And will there ever be peace with the Klingons?—Colin Tinto <cst@imdb.com>

After a lunar cataclysm brings the Klingons to their knees, the foreign concept of peace with the Federation may be finally within reach. After 70 years of hostility, the Federation and the Klingon Empire prepare for a peace summit. Ironically, Captain James T. Kirk has been assigned as the first emissary to broker that peace. However, the prospect of intergalactic glasnost with sworn enemies is an alarming one. When the Klingon flagship is attacked and the USS Enterprise is held accountable, the dogs of war are unleashed again, as both worlds brace for what may be their final, deadly encounter.—Robert Lynch <docrlynch@yahoo.com>

In 2293, the starship USS Excelsior, commanded by Captain Hikaru Sulu (George Takei), is struck by a shockwave when the Klingon moon Praxis explodes without warning, and its crew discovers that much of the moon has been obliterated. The loss of their key energy production facility and the destruction of the Klingon home world's ozone layer throws the Klingon Empire into turmoil. The explosion of the moon was caused by over mining and insufficient safety precautions.

No longer able to maintain a hostile footing, the Klingons sue for peace with their longtime enemy, the United Federation of Planets. Accepting the proposal before the Klingons reverse to a more hostile approach, Starfleet sends the USS Enterprise-A to meet with the Klingon Chancellor Gorkon (David Warner) and escort him to negotiations on Earth. Captain James T. Kirk (William Shatner), whose son David was murdered by Klingons years earlier, opposes the negotiations and resents his assignment. The other officers are Leonard McCoy (DeForest Kelley), the chief medical officer; Montgomery Scott (James Doohan), the Enterprise's chief engineer; Pavel Chekov (Walter Koenig), the Enterprise's navigator; and Uhura (Nichelle Nichols), the ship's communications officer.

After a rendezvous between the Enterprise and Gorkon's battle cruiser they continue towards Earth, with the crews sharing a tense dinner aboard the Enterprise. Later that night, the Enterprise appears to fire on the Klingon ship with a pair of photon torpedoes, disabling the artificial gravity aboard the Klingon vessel. During the confusion, two figures wearing Starfleet suits and gravity boots beam aboard the Klingon ship and mortally wound Gorkon before beaming away. The situation is chaotic on the Enterprise, Scotty confirms that all torpedoes are into place, yet the data banks suggest that the Enterprise has fired twice upon the Klingon ship. Kirk surrenders to avoid armed conflict and beams aboard the Klingon ship with Doctor McCoy to attempt to save Gorkon's life.

The chancellor dies, and Gorkon's chief of staff, General Chang (Christopher Plummer), arrests and puts Kirk and McCoy on trial for his assassination. The pair are found guilty by a Klingon court and sentenced to life imprisonment on the frozen asteroid Rura Penthe. Gorkon's daughter Azetbur (Rosanna DeSoto) becomes the new chancellor, and continues diplomatic negotiations; for reasons of security, the conference is relocated and the new location is kept secret. While several senior Starfleet officers want to rescue Kirk and McCoy, the Federation president (Kurtwood Smith) refuses to risk full-scale war. While several Klingon generals want to attack, Azetbur refuses to invade Federation space, stating that only Kirk and McCoy will pay for her father's death.

Kirk and McCoy arrive at the Rura Penthe mines and are befriended by a shapeshifter named Martia (Iman), who offers them an escape route; in real life, it is a deception to make their arranged deaths appear accidental. Once her betrayal is revealed, Martia transforms into Kirk's double and fights him, but she is killed by the prison guards to silence any witnesses. Just before the prison warden reveals who set them up, Kirk and McCoy are beamed aboard the Enterprise by Captain Spock (Leonard Nimoy), who had assumed command and undertaken an investigation during Kirk's absence.

Determining that the Enterprise did not fire the torpedoes but that the assassins are still aboard, the crew begins looking for them. The two assassins are found dead, but Kirk and Spock deceive their accomplice into believing they are still alive. When the blamed person arrives in sickbay to kill the assassins, Kirk and Spock discover that the killer is Spock's protege, Lieutenant Valeris (Kim Cattrall). To discover the identity of the conspirators, Spock initiates a forced mind-meld, and learns that a group of Federation, Klingon and Romulan officers plotted to sabotage the peace talks, fearing the changes their success might bring (the titular "undiscovered country"), and Chang is one of the conspirators. The torpedoes that struck Gorkon's cruiser came from a prototype Bird of Prey that can fire while cloaked and hovered just below the Enterprise at the time of the assassination.

The crew contacts Sulu, who informs them the conference is being held at Camp Khitomer. Both ships head for the peace talks as fast as they can. As the Enterprise nears the planet, Chang's cloaked Bird of Prey moves into intercept. With the Enterprise unable to track his ship's position, Chang inflicts severe damage on the Enterprise and then the Excelsior. At the suggestion of Uhura, Spock and McCoy modify a photon torpedo to home in on the exhaust emissions of Chang's vessel, using equipment originally intended to study gaseous anomalies. The torpedo impact reveals Chang's location, and the Enterprise and the Excelsior destroy the Bird of Prey with a volley of torpedoes. The crew from both ships beam to the conference and prevent an attempt on the Federation president's life. Kirk pleads for those present to continue the peace process, noting that history has not ended quite yet.

Having saved the peace talks, the Enterprise is ordered back to Earth by Starfleet Command to be decommissioned, but the crew decide to take their time on the return voyage. As the Enterprise cruises towards a nearby star, Kirk proclaims that though this mission is the final cruise of the Enterprise under his command, others will continue their voyages.