A fire starts aboard the Colonial Marine spaceship Sulaco. The computer launches an escape pod containing Ellen Ripley, the young girl Newt, an unidentified man, and the damaged android Bishop. All four are in cryonic stasis. The ship's scans of the crew's cryotubes show an Alien facehugger attached to one of the crew members. The pod crash-lands on Fiorina "Fury" 161, a foundry facility and penal colony inhabited by male inmates with "double-Y" chromosome patterns and histories of physical and sexual violence. After some inmates recover the pod and its passengers, an Alien facehugger approaches the prison dog.
Captain Jean-Luc Picard wakes from a nightmare in which he relived his assimilation by the cybernetic Borg six years earlier (shown in the television episode "The Best of Both Worlds"). Starfleet informs him of a new Borg attack against Earth, but orders the USS Enterprise-E to patrol the Romulan Neutral Zone so as not to introduce an "unstable element" to the fight. Learning that the fleet is losing the battle, the Enterprise crew disobeys orders and heads for Earth, where a single, damaged Borg Cube opposes a group of Starfleet vessels. The Enterprise arrives in time to save the crew of the USS Defiant which is being commanded by Lieutenant Commander Worf. After Picard hears Borg communications in his mind, he orders the fleet to concentrate its firepower on a seemingly non-vital section of the Borg ship. The Cube is destroyed after launching a smaller sphere ship towards the planet.
In 2273, a Starfleet monitoring station, Epsilon Nine, detects an alien force, hidden in a massive cloud of energy, moving through space towards Earth. The cloud destroys three of the Klingon Empire's new K't'inga-class warships and the monitoring station en route. On Earth, the starship Enterprise is undergoing a major refit; her former commanding officer, James T. Kirk, has been promoted to Admiral and works in San Francisco as Chief of Starfleet Operations. Starfleet dispatches Enterprise to investigate the cloud entity as the ship is the only one in intercept range, requiring her new systems to be tested in transit.
In the year 2058, Earth will soon be uninhabitable due to irreversible effects of pollution. The United Global Space Force prepares the first launch for the colonization of a distant planet much like our own. Meanwhile, a terrorist group, the Global Sedition, wants to interrupt the colonization to be able to take over the same planet themselves. Professor John Robinson, lead scientist of the Jupiter Mission, prepares to take his wife Maureen, daughters Judy and Penny and son Will on a 10-year mission in suspended animation to the nearby planet Alpha Prime, where they will build a companion "hypergate" to the one orbiting Earth. The project is accelerated after Global Sedition terrorists attack Earth's hypergate, but are stopped by fighter pilots, one of whom is Major Don West. When the pilot for the Jupiter Mission is murdered, West is assigned as his replacement.
In 2286, a large cylindrical probe moves through space, sending out an indecipherable signal and disabling the power of ships it passes. As it takes up orbit around Earth, its signal disables the global power grid and generates planetary storms, creating catastrophic, sun-blocking cloud cover. Starfleet Command sends out a planetary distress call and warns starships not to approach Earth.
Following the events of Alien vs. Predator, a Predator ship is leaving Earth carrying Alien facehuggers, and the body of Scar, the Predator that defeated the Alien Queen. A chestburster erupts from Scar's body; it is a new creature that is a hybrid of both species. It quickly matures into an adult Predalien and starts killing all the Predators on the ship. A Predator's weapon fire punctures the hull and the ship crashes in the forest outside of Gunnison, Colorado.
In 1958, two U.S. Air Force pilots and aspiring astronauts, William "Hawk" Hawkins (Tommy Lee Jones) and Frank Corvin (Clint Eastwood), are testing a modified X-plane when Hawk decides to try to break a height record. The plane stalls and they are forced to eject, narrowly missing a B-50 Superfortress piloted by navigator "Tank" Sullivan (James Garner) as they parachute to safety. On the ground, Frank punches Hawk for putting their lives at risk, but their fight is broken up by engineer Jerry O'Neill (Donald Sutherland). Their supervising officer, Bob Gerson (James Cromwell), chastises Hawk for his recklessness, before taking them to a press conference, where it is announced that the Air Force will no longer be involved in space flight tests as this has now been handed off to the newly created NASA, ending the four's dreams of reaching space.
Sur Terre, dans un futur proche, l’ingénieur et astronaute de la NASA Roy McBride s'occupe de la maintenance d'une antenne de 30 km de hauteur. Celle-ci est détruite lors d’une surcharge électrique venue de Neptune, qui cause des ravages également sur Terre.
In the 23rd century, Earth has become a space-faring federation. While colonizing new planets, humans have encountered an insectoid species known as Arachnids or "Bugs", with their home being the distant world Klendathu. The bugs appear to be little more than killing machines, though there are suggestions that they were provoked by the intrusion of humans into their habitats.
In the year 2293, retired Captain James T. Kirk, Montgomery Scott, and Pavel Chekov attend the maiden voyage of the Federation starship USS Enterprise-B, under the command of the unseasoned Capt. John Harriman. During the voyage, Enterprise is pressed into a rescue mission to save two El-Aurian ships from a strange energy ribbon. Enterprise is able to save some of the refugees before their ships are destroyed, but the starship becomes trapped in the ribbon. Kirk goes to deflector control to alter the deflector dish, allowing Enterprise to escape, but the trailing end of the ribbon rakes across Enterprise 's hull, exposing the section Kirk is in to space; he is presumed dead.
Lieutenant Commander Data (Brent Spiner) is temporarily transferred to an undercover mission observing the peaceful Ba'ku people. While on their planet, he malfunctions and reveals the presence of the joint Federation–Son'a task force observing the Ba'ku. Admiral Matthew Dougherty (Anthony Zerbe) contacts the USS Enterprise-E to obtain Data's schematics but adamantly states the presence of the Enterprise is not needed. Captain Picard decides to ignore these orders and takes the Enterprise to capture Data. After stopping Data, Captain Jean-Luc Picard (Patrick Stewart) becomes suspicious of Dougherty's insistence that the Enterprise is no longer needed. His crew investigates the cause of Data's malfunction. They discover that the Ba'ku are technologically advanced, but have rejected its use to live simpler lives. Due to unique radiation or "metaphasic particles" emanating from their planet's rings, they are effectively immortal. Dougherty's allies, the Son'a, are a decrepit race who use medical techniques to prevent death; their excessive use of cosmetic surgery gives them a mummified appearance. The Enterprise crew also begin to experience the rejuvenation effects of the planet: Lt. Commander Geordi La Forge (LeVar Burton) finds his eyes have regenerated and he no longer requires ocular implants; Commander William Riker (Jonathan Frakes) and Counselor Deanna Troi (Marina Sirtis) rekindle their long-abandoned relationship; and Picard develops a romantic relationship with the Ba'ku woman Anij (Donna Murphy).
After escaping the dark planet, Richard B. Riddick has been in hiding for five years, evading most of the bounty hunters and mercenaries that are set to capture him because of his high price on his head. His latest hideout is a Planet U.V., a world lit only by ultraviolet light.
The commercial spacecraft Nostromo is on a return trip to Earth with a seven-member crew in stasis. Detecting a mysterious transmission, possibly a distress signal, from a nearby planetoid, the ship's computer, MOTHER, awakens the crew. Following standard company policy for such situations, the Nostromo lands on the planetoid and Captain Dallas, Executive Officer Kane, and Navigator Lambert head out to investigate. They discover the signal is coming from a derelict alien spacecraft. Inside, they find the remains of a large alien creature whose ribcage appears to have exploded from the inside.
The film begins with a Broadway-style number "So Long, and Thanks for All the Fish", sung by the dolphins of the world, who are aware of the Earth's impending doom. At the end, they all jump out of the oceans and into space, leaving Earth for good.
Six membres de l'équipage de la Station spatiale internationale (ISS) réceptionnent une sonde revenant de Mars et contenant un échantillon de sol, qui pourrait contenir des signes de vie extraterrestre. L’exobiologiste Hugh Derry relance une cellule dormante de l'échantillon, et il se développe rapidement en un organisme multi-cellulaire. La mission est suivie sur Terre par la population. Un concours est même lancé pour donner un nom à l'organisme. Des écoliers américains le nomment Calvin.