The crew of the newly commissioned USS Enterprise (NCC-1701-A) are enjoying shore leave after the starship’s shakedown cruise. At Yosemite National Park, Captain James T. Kirk is camping with First Officer Spock and Dr. Leonard McCoy. Their leave is interrupted when the Enterprise is ordered by Starfleet Command to rescue the three human, Klingon, and Romulan diplomats taken hostage on Nimbus III, a planet set aside as a neutral location to advance dialogue between the Federation, Klingon Empire, and Romulan Star Empire. Learning of the Enterprise’s mission, the ambitious Klingon captain Klaa decides to pursue Kirk for personal glory.
On Nimbus III, the Enterprise crew discovers that a renegade Vulcan, Sybok (who is Spock’s half-brother), is behind the hostage crisis. Sybok reveals that the hostage situation was a ruse to lure a starship to Nimbus III, which he intends to use to reach the mythical planet Sha Ka Ree, the place where creation began; the planet lies behind a seemingly impenetrable field known as the Great Barrier around the center of the galaxy. Sybok uses his unique ability to reveal and heal the innermost pain of a person through the mind meld to subvert the hostages’ and crew members’ wills. McCoy’s pain is that he had helped fulfill his terminally ill father’s request to die only to later find that a cure could have saved his father’s life, which caused McCoy years of guilt. Spock’s pain is the knowledge that his father rejected him at birth because he was “too human.” Only Spock and Kirk prove resistant to Sybok’s influence. Spock is unmoved by the experience and Kirk refuses the Vulcan’s offer, telling him that his pain is necessary to make him human. Sybok reluctantly declares a truce with Kirk, realizing that he needs his leadership experience to navigate the Enterprise to Sha Ka Ree.
The ship successfully breaches the Great Barrier, pursued by Klaa’s warship (a Klingon bird-of-prey), and discovers a lone, uninhabited planet. Sybok, Kirk, Spock, and McCoy take a shuttlecraft to the surface, where Sybok calls out to his perceived vision of the creator. An entity appears, represented as a large human face, and when told of how Sybok breached the barrier, demands that the Enterprise be brought closer to the planet. When a skeptical Kirk asks, “What does God need with a starship?”, the entity attacks him in retribution. The others discover that the “creator” has deceived them and that the barrier is, in fact, intended to prevent it from escaping Sha Ka Ree.
Horrified by his naiveté, Sybok sacrifices himself in an effort to combat the creature and allow the others to escape. Intent on stopping the entity, Kirk orders the Enterprise to fire a photon torpedo at their location, to little effect. Spock and McCoy are beamed back to the ship, but Klaa attacks the Enterprise before Kirk can be transported aboard. The vengeful entity reappears and tries to kill Kirk before the Klingons destroy it in a volley of disruptor fire. Kirk is beamed aboard the Klingon ship, where Spock is waiting. General Korrd orders Klaa to stand down and to apologise to Kirk for his actions. After the crews of Enterprise and the Klingon ship celebrate a new détente, Kirk, Spock, and McCoy are permitted to resume their shore leave at Yosemite.
Star Trek Command 