“The line must be drawn HERE! This far, no farther! I…will make them PAY for what they’ve done!”
Captain Jean-Luc Picard ranting about the Borg
When producers started making the eighth Star Trek film, they knew it had to deliver big. The previous film was successful but received criticisms over its quality. So for Star Trek: First Contact they brought out the big guns in the form of the Borg, the most popular villains on the TV show Star Trek: The Next Generation (TNG). And it worked.
It opens with a close up shot of Captain Jean-Luc Picard (Patrick Stewart) looking straight ahead. The camera pulls back to reveal he’s inside the nightmarish machinery of a Borg vessel. What’s worse is his transformation into one of them and losing his identity. The Borg are a cold, and nearly invincible cyborg race made up of assorted aliens that are forcibly converted using painful looking cybernetic implants. They seek the perfect union between machine and life and assimilating other races to achieve this objective.
Picard eventually wakes up from the nightmare, which was a flashback to his ordeal in the classic two-part episode “The Best Of Both Worlds”. He’s onboard his new ship, the Enterprise-E and receives news that the Borg have returned to Federation space. However, instead of being ordered to join an assembled armada to fight the Borg, he is to patrol the Romulan Neutral Zone with his ship.
He and his crew are visibly restless about their orders. Later as they carry them out, his first officer Will Riker (Jonathan Frakes) complains about the orders, Picard tells him that Starfleet feels that his own experiences with being turned into a Borg will compromise his ability to fight them.
Just then he and the crew pick up transmissions from the fight. Things aren’t going well for the Starfleet armada, it’s losing badly to the Borg. Having heard enough, Picard decides to disobey orders and join the fight, with his crew behind him. The Enterprise-E then warps off at its highest speed to Earth.
The very next scene features a mammoth and imposing Borg cube that fills the screen, accompanied by a booming score, as it nears our planet. It’s slammed by weapons fire from Starfleet ships. Unlike “The Best Of Both Worlds” the ships are putting up a better fight, but are still losing. New and eye-catching Starfleet ships abound, one of them is the Defiant, the scrappy escort vessel seen in the TV show Star Trek: Deep Space Nine (DS9). Commanding the Defiant is the Klingon Lt. Commander Worf (Michael Dorn), who in between films, joined DS9. His damaged ship is caught in a tractor beam from the cube.
The Enterprise-E suddenly joins the fray, rescues the Defiant and beams aboard its survivors. Moments later, Worf joins his old comrades at the bridge, completing the film reunion. Picard takes command of the fleet and orders a simultaneous barrage of weapons fire at specific spots on the cube.
In a spectacular display, the Starfleet ships fire a vicious volley at the Borg cube and destroy it. However, before it explodes, the cube releases a smaller, sphere-shaped vessel that rushes towards Earth.
The Enterprise-E is on its tail as a temporal vortex opens up in front of the Borg sphere that leaves behind 
an energy wake that washes over the Enterprise-E. After the sphere disappears into the vortex, the horrified crew of the starship see the Earth before them become Borgified. The planet’s colorful landmasses are transformed into one continuous field of metallic grey.
They deduce that the sphere traveled to Earth’s past and assimilated the planet. The ship’s android operations officer Lt. Commander Data (Brent Spiner) theorizes that the wake protected them from being changed with the altered timeline. Before the vortex can close, Picard orders the Enterprise-E to go through it.
The sphere emerges from the vortex and begins attacking a small, rundown town in Montana. The Enterprise-E arrives a few minutes later and destroys the sphere. They learn they’re in the mid 21st century, April 4, 2063 to be exact, about ten years after World War III. Based on that information, Picard realizes that the Borg want to stop Zefram Cochrane, the human inventor of warp drive technology, from successfully testing Earth’s first warp drive ship, the Phoenix. Its flight on the next day will attract the attention of a passing Vulcan ship, which will then travel to Earth. The resulting peaceful first contact will eventually lead to the founding of the United Federation of Planets.
Fearing the worst, Picard with an Away Team beams down to the town, which actually has a missile complex. 
Even though most of the personnel in the complex are dead, Cochrane’s assistant and co-pilot Lily Sloane (Alfre Woodard) is found alive but suffering from radiation poisoning. She’s taken back to the ship for treatment by Chief Medical Officer Dr. Beverly Crusher (Gates McFadden) while Picard looks for Cochrane. The Phoenix (actually a converted nuclear missile) is damaged but repairable.
Throughout the film, Picard was able to hear Borg voices in his head, a residual effect of his ordeal after being assimilated. He hears them again and returns to the ship with Data, while having Riker beam down to continue looking for Cochrane. Chief Engineer Geordi LaForge (Levar Burton) also beams down with a team to repair the Phoenix and continue with the planned flight.
Back on the Enterprise-E, the bridge crew discover that they are losing control over several systems and cannot contact main engineering. It soon becomes apparent that there are Borg drones onboard the starship. The captain theorizes that before the sphere was destroyed several Borg must’ve beamed onboard undetected to assimilate the starship. Acting quickly, Picard orders Data to lock out the main computer and heads to main engineering with a security team. Picard’s plan is to puncture the warp core’s plasma coolant tanks, which will flood engineering and liquefy all organic matter, namely the Borg’s organic parts.
When they get near their destination, several Borg drones, many of whom are assimilated crewmembers, attack Picard’s detail. They’re forced to retreat but Data is captured.
During his retreat, Picard runs into Lily, who evacuated sickbay and separated from Crusher’s medical team after the Borg broke into the medical facility. Lily doesn’t know what is going on and orders Picard at phaser point to be taken back home. PIcard is able to convince her that she is on a ship from the future and takes her with him to a holodeck. They briefly hide there while a 1940s detective story simulation plays until two Borg enter the holodeck. Picard begins to exhibit his inner rage and transforms into a movie action hero while killing them with a holographic Tommy gun. Then he retrieves a neural processor from one of the corpses to learn the Borg’s plans.
One of them is to use the ship’s deflector to contact other Borg for reinforcements. This leads to one of the film’s most suspenseful moments: a dangerous battle with the enemy outside on the ship’s outer hull. They’re truly inhuman with their capability to function without spacesuits, while Picard, Worf and a redshirt named Hawk (Neal McDonough) donned sleek, white EV suits.
