In the 23rd century, a Starfleet monitoring station, Epsilon Nine, detects an alien entity, hidden in a massive cloud of energy, moving through space toward Earth. The cloud easily destroys three Klingon warships and Epsilon Nine on its course. On Earth, the starship Enterprise is undergoing a major refit; its former commanding officer, James T. Kirk, has been promoted to Admiral. Starfleet Command assigns Enterprise to intercept the cloud entity, as the ship is the only one within range, requiring its new systems to be tested in transit.
Citing his experience, Kirk uses his authority to take command of the ship, angering Captain Willard Decker, who has been overseeing the refit as its new commanding officer. Testing of Enterprise’s new systems goes poorly; two officers, including the ship’s Vulcan science officer Sonak, are killed by a malfunctioning transporter, and improperly calibrated engines nearly destroy the ship. Kirk’s unfamiliarity with the ship’s new systems increases the tension between him and Decker, who has been temporarily demoted to commander and first officer. Commander Spock arrives as a replacement science officer, explaining that while on his home world undergoing a ritual to purge himself of emotion, he felt a consciousness that he believes emanates from the cloud, making him unable to complete the ritual because his human half felt an emotional connection to it.
Enterprise intercepts the energy cloud and is attacked by an alien vessel within. A probe appears on the bridge, attacks Spock, and abducts the navigator, Ilia. She is replaced by a robotic replica, sent by the entity, which calls itself “V’Ger”, to study the “carbon units” on the ship. Decker is distraught over the loss of Ilia, with whom he had a romantic history, and becomes troubled as he attempts to extract information from the doppelgänger, which has Ilia’s memories and feelings buried inside. Spock takes an unauthorized spacewalk to the vessel’s interior and attempts a telepathic mind meld with it. In doing so, he learns that the entire vessel is V’Ger, a non-biological living machine.
At the center of the massive ship, V’Ger is revealed to be Voyager 6, a 20th-century Earth space probe believed lost in a black hole. The damaged probe was found by an alien race of living machines that interpreted its programming as instructions to learn all that can be learned and return that information to its creator. The machines upgraded the probe to fulfill its mission, and on its journey, the probe gathered so much knowledge that it achieved sentience. Spock discovers that V’Ger lacks the ability to give itself a purpose other than its original mission; having learned everything it could on its journey home, it finds its existence meaningless. Before transmitting all its information, V’Ger insists that the “Creator” come in person to finish the sequence. Everyone realizes humans are the Creator. Decker offers himself to V’Ger; he merges with the Ilia probe and V’Ger, creating a new life form that disappears into space. With Earth saved, Kirk directs Enterprise out to space for future missions.
Star Trek Command 