After the critical and commercial disappointment of The Final Frontier, the next film was initially planned as a prequel, with younger actors portraying the crew of the Enterprise while attending Starfleet Academy.

Faced with producing a new film in time for Star Trek's 25th anniversary, director Nicholas Meyer and Denny Martin Flinn wrote a script based on a suggestion from Leonard Nimoy about what would happen if "the Wall came down in space", touching on the contemporary events of the Cold War.

Kirk and McCoy arrive at the Rura Penthe mines and are befriended by a shapeshifter named Martia, who offers them an escape route; in reality, it is a ruse to make their arranged deaths appear accidental.

[8] With the looming 25th anniversary of the original series in 1991, producer Harve Bennett revisited an idea Ralph Winter had for the fourth film: a prequel featuring young versions of Kirk and Spock at Starfleet Academy.

[20] Nimoy, Mark Rosenthal and Lawrence Konner suggested Kirk meeting Jean-Luc Picard, but Star Trek: The Next Generation's producers refused to end their show.

After they produced minimal, if any, usable material and appeared unlikely to make the deadline to start filming, Nimoy was able to reconcile with Meyer so he could write the script and Konner and Rosenthal were let go.

[13] The revised opening featured Captain Sulu bringing his friends out of their retirement: Spock's whereabouts are classified; Kirk was to have married Carol Marcus (played by Bibi Besch in The Wrath of Khan), the mother of his late son, leading a settled life before a special envoy arrives at his door.

McCoy is drunk at a posh medical dinner; Scott is teaching Engineering while the Bird of Prey from The Voyage Home is pulled from San Francisco Bay; Uhura hosts a call-in radio show and is glad to escape; and Chekov is playing chess at a club.

[28]: 44 The corridors were reduced in width and included angled bulkhead dividers, with exposed conduits added to the ceiling to convey a claustrophobic feel reminiscent of the submarine film The Hunt for Red October.

None of the actors wanted to eat the unappetizing dishes (especially after they grew ripe under hot studio lights),[13] and it became a running joke among the crew during filming to make them sample their food.

While the Khitomer conference interior and exteriors were filmed at the Brandeis-Bardin Institute in California, the window from which Colonel West prepares to assassinate the president was a separate set built at Paramount.

Elements of the zero gravity scenes were handled by Pacific Data Images, while phaser beams and transporter effects were generated by Visual Concept Engineering, an offshoot of ILM that had contributed to The Wrath of Khan and The Final Frontier.

[5]: 42  ILM's ring-shaped "Praxis Effect" shockwave became a common feature in science fiction films depicting the destruction of large objects, while astronomer Philip Plait assumed that in reality a spherical wave would be more likely.

[13] For the final space battle, Bill George redesigned the photon torpedoes to have a hotter core and larger flare, because he felt that the weapons in earlier films looked "too pretty".

[35]: 8 In conversations with Eidelman, Meyer mentioned that since the marches that accompanied the main titles for the previous Star Trek films were so good, he had no desire to compete with them by composing a bombastic opening.

[35]: 9 Eidelman stated that he finds science fiction the most interesting and exciting genre to compose for, and that Meyer told him to treat the film as a fresh start, rather than drawing on old Star Trek themes.

[8] Eidelman wanted the music to aid the visuals; for Rura Penthe, he strove to create an atmosphere that reflected the alien and dangerous setting, introducing exotic instruments for color.

The final line spoken by Chang before he is obliterated by torpedo fire is lifted from Hamlet's famous soliloquy: "to be, or not to be..."[41]: 8  Flinn was initially unsure about the numerous classical quotations, but when Plummer was cast, Meyer enthusiastically added more.

[44] As the Enterprise crew works to identify Gorkon's assassins, acting Captain Spock invokes "an ancestor of mine" who maintained that when the impossible is eliminated, what remains must be true, no matter how unlikely it is.

[22] While Star Trek in general features few overt references to religion, there is a clear recognition that a laying aside of past hurts is necessary for peace, similar to the concept of shalom in Judaism.

[60][61] Audiences surveyed by CinemaScore gave the film a grade "A−" on scale of A to F.[62] The Herald Sun reported that "those who found The Final Frontier weighed down by emotional gravity and over-the-top spiritualism [welcomed] the follow-up with its suspense, action and subtle good humor.

"[61] Critic Hal Hinson commented that Meyer "[is] capable of sending up his material without cheapening it or disrupting our belief in the reality of his yarn," and called the one-liners an organic part of the film's "jocular, tongue-in-cheek spirit".

[64] Susan Wloszczyna of USA Today said that with Meyer directing, "this last mission gets almost everything right—from the nod to late creator Gene Roddenberry to in-jokes about Kirk's rep as an alien babe magnet.

[66] Rob Salem of The Toronto Star quipped that though the actors looked silly on occasion, this was a benefit; "as their capacity for action has diminished, their comedic talents have blossomed [...] they have all become masters of self-deprecating self-parody.

Mary Boson of the Sydney Morning Herald considered the comparisons to real-world situations timely, and praised the plot for exploring the reactions of those who have invested themselves in a life of belligerence.

[73] Instead of maintaining suspense, The Washington Times's Gary Arnold noted the Rura Penthe sideplot offered "scenic distraction without contributing significantly to the whodunit crisis [...] The crime itself has a promising 'closed-room' aspect that never gets elaborated adequately [...] You look forward to a cleverly fabricated solution."

[76] The special effects were alternately lauded and criticized; USA Today called them "just serviceable", though Wloszczyna's review for the paper said the Klingon assassination sequence was "dazzling", with "fuchsia blood spilling out in Dalí-esque blobs".

[65] Desson Howe, writing for The Washington Post's Weekend section, said that "the Klingons' spilled blood floats in the air in eerily beautiful purplish globules; it's space-age Sam Peckinpah.

The site's critics' consensus reads: "The Undiscovered Country is a strong cinematic send-off for the original Trek crew, featuring some remarkable visuals and an intriguing, character-driven mystery plot.

"[21] Among the elements added for home video were a briefing with the Federation president where Admiral Cartwright and Colonel West unveil their plan for rescuing Kirk and McCoy, and a scene where Spock and Scott inspect the torpedoes.