The Borg travel back in time intent on preventing Earth's first contact with an alien species. Captain Picard and his crew pursue them to ensure that Zefram Cochrane makes his maiden flight reaching warp speed.
In the twenty-fourth century, the crew of the U.S.S. Enterprise NCC-1701-E has been ordered to patrol the Romulan Neutral Zone by the Federation to avoid interference with their battle against the insidious Borg. Witnessing the loss of the battle, Captain Jean-Luc Picard ignores orders and takes command of the fleet engaging the Borg. But the Borg plan to travel back into the twenty-first century through a vortex with the intention to stop Earth's first contact with an alien race (the Vulcans). Following the Borg sphere, Picard and his crew realize that they have taken over the Enterprise in order to carry out their mission. Their only chance to do away with the Borg and their seductive Queen is to make sure that Zefram Cochrane makes his famous faster-than-light travel to the stars.
The Borg have invaded Earth's galaxy, resulting in a battle with Star Fleet. The newly-commissioned USS Enterprise-E, commanded by Captain Jean-Luc Pickard, is ordered away from the action as Star Fleet command fear that Pickard's previous assimilation by the Borg will affect his judgement. Once it is clear that Star Fleet are losing the battle, Pickard disobeys orders and sets course for Earth, arriving in the nick of time. The Enterprise manages to save the Earth from destruction but it is soon apparent that the Borg do not intend to destroy Earth but change the course of its history.
It is the twenty-fourth century, and the Borg (cybernetic lifeforms) have spread across the galaxy with one sole purpose: to assimilate and conquer all races. Under the command of their seductive and sadistic Queen, the Borg are headed to Earth with a devious plan involving time travel to alter history. After an epic battle against the Borg, Captain Jean-Luc Picard and the U.S.S. Enterprise NCC-1701-E crew follow the Borg sphere back into the twenty-first century, and must battle the Borg Queen before she assimilates mankind. Meanwhile, Picard and his crew must make sure that Zefram Cochrane makes his famous warp flight, and makes Earth's first contact with an alien species (the Vulcans).
- Captain Jean-Luc Picard (Patrick Stewart) awakens from a nightmare in which he relived his assimilation by the Borg (cybernetic lifeforms) six years earlier. He is contacted by Admiral Hayes, who informs him of an imminent Borg invasion against Earth. Picard's orders are for his ship, the USS Enterprise-E, to patrol the Neutral Zone in case of Romulan aggression, as Starfleet is worried that Picard is too emotionally involved with the Borg to join the fight. Learning the fleet is losing the battle, the Enterprise crew disobeys orders and heads for Earth, where a single Borg Cube holds its own against a group of Starfleet vessels. The Enterprise arrives in time to save the crew of the USS Defiant and its captain, the Klingon Worf (Michael Dorn). Picard takes command of the fleet and orders the surviving ships to concentrate their firepower on a seemingly unimportant point on the Cube. The Cube is destroyed after launching a small sphere towards the planet. The Enterprise pursues the sphere into a temporal vortex. As the sphere disappears, the Enterprise discovers Earth has been altered; it is now populated entirely by Borg. Realizing the Borg have used time travel to change the past, the Enterprise follows the sphere through the vortex.
The Enterprise arrives in the past on April 4, 2063, the day before humanity's first encounter with an alien species after Zefram Cochrane's (James Cromwell) historic warp flight; the crew realizes the Borg are trying to prevent "first contact." The sphere opens fire on Cochrane's site in Bozeman, Montana, where he's building his warp drive craft from an abandoned nuclear missile. After destroying the Borg sphere, the away team is met with hostile resistance by Cochrane and his assistant, Lily Sloane (Alfre Woodard), who suffers radiation poisoning from a leaking container damaged in the attack.
Picard has Sloane sent back to the Enterprise for medical attention. The Captain returns to the ship and leaves Commander William Riker (Jonathan Frakes) on Earth to make sure the Phoenix's flight proceeds as planned. While in the future Cochrane is seen as a hero, the real man, a burnout from the wars that devastated Earth and a mild alcoholic, is reluctant to assume the role the Enterprise crew describe. He initially disbelieves their story but is swayed when they're able to prove the Enterprise-E exists and is in orbit above them.
A group of Borg invade the Enterprise's lower decks and begin to assimilate her crew and modify the ship. Picard and a team attempt to reach engineering to disable the Borg with a corrosive gas, but are forced back; the android Data (Brent Spiner) is captured in the melee. Frightened, Sloane corners Picard with a phaser, but he gains her trust, showing her that she's on a spacecraft orbiting Earth. The two escape the Borg-infested area of the ship by creating a diversion in the holodeck. Picard, Worf, and the ship's navigator, Lt. Sean Hawk (Neal McDonough), travel outside the ship in space suits to stop the Borg from calling reinforcements by using the deflector dish. As the Borg continue to assimilate more decks, Worf suggests destroying the ship, but Picard angrily calls him a coward and vows to continue the fight. Sloane confronts the captain and makes him realize he is behaving irrationally on account of his desire for revenge. Chastened, Picard relents, apologizes to Worf, and orders the activation of the ship's self-destruct sequence. While the crew head for escape pods, the Captain decides to stay behind and rescue his friend Data.
As Cochrane, Riker, and Chief Engineer Geordi La Forge (LeVar Burton) prepare to activate the warp drive on the Phoenix, Picard discovers that the Borg Queen (Alice Krige) has grafted human skin onto Data. She presented this modification with the sensations he has long desired, hoping to obtain the android's encryption codes for the Enterprise computer. Although Picard offers himself to the Borg in exchange for Data's freedom, Data refuses to leave. He deactivates the self-destruct mechanism and fires torpedoes at the Phoenix. At the last moment, the torpedoes miss the Phoenix, and the Borg Queen realizes Data has betrayed her. The android ruptures a coolant tank, and the corrosive vapor eats away the biological components of the Borg. With the Borg invasion neutralized, Cochrane completes his warp flight. After Picard finishes off the Queen's twitching remains, Data confesses that he was tempted by her offer, for 0.68 seconds, but after that eternity by his perception, he rejected it and strung her along to enable her defeat.
The next day at the missile complex, the crew watches from a distance as a Vulcan survey ship, attracted by the Phoenix's warp flight, lands on Earth. While Cochrane goes to greet the aliens, Sloane notices the Enterprise crew slipping away. She bids Picard farewell, envious of the happy future he is returning to. Picard reminds her that it is a future that she and her friends are going to make possible. Having ensured the correction of the timeline, the Enterprise crew return to the 24th century.