At the White House, a teleporting mutant, Nightcrawler, attacks the President of the United States; he is shot and retreats. Meanwhile, Logan explores an abandoned military installation at Alkali Lake in Alberta for clues to his past, but finds nothing. Jean Grey has been having premonitions and struggles to concentrate as her powers become increasingly difficult to control. Later, Logan returns to Professor Xavier 's school for mutants, and Xavier tracks Nightcrawler using Cerebro. Xavier and Cyclops go to question the imprisoned Magneto about the attack, while Jean and Storm retrieve Nightcrawler. Military scientist Colonel William Stryker approaches the President and receives approval to investigate Xavier's mansion for their ties to mutants after the recent attack. Stryker's forces invade the school and abduct some of the students. Colossus leads the remaining students to safety while Logan, Rogue, Iceman, and Pyro escape. Stryker's assistant Yuriko Oyama captures Cyclops and Xavier. During the attack, Logan confronts Stryker, who addresses him as "Wolverine" and appears to be aware of his past. The shapeshifting mutant, Mystique, helps Magneto escape and finds Cerebro schematics. Logan, Rogue, Iceman, and Pyro visit Iceman's family in Boston. Iceman's brother calls the police after learning he's a mutant. Officers surround the house; one shoots Logan after feeling threatened. Pyro fights back against officers with his pyrokinesis before Storm, Jean, and Nightcrawler pick them up in their jet. The X-Jet is attacked by fighter jets and shot down while returning to the mansion, but Magneto saves them. He explains that Stryker built a second Cerebro to kill every mutant telepathically, using his mutant son Jason, who can control minds, to coerce Xavier. Stryker previously used Jason's powers on Nightcrawler to attack the White House to justify his excuse for invading Xavier's mansion. Magneto also tells Logan that Stryker grafted adamantium onto his bones and caused his amnesia. Jean discovers Stryker's underground base in a dam at Alkali Lake. Disguised as Logan, Mystique infiltrates Stryker's base, letting mutants in while she and Magneto head to disable Cerebro before Xavier, brainwashed, can activate it. Storm and Nightcrawler rescue students, and Jean fights a mind-controlled Cyclops; their fight frees Cyclops but damages the dam, causing it to rupture. Logan finds Stryker in an adamantium smelting lab, recalling where he got his skeleton. Logan fights and kills Yuriko, then chases Stryker to a helicopter pad and chains him to the wheel. Magneto stops Cerebro and, with Mystique impersonating Stryker to command Jason, has Xavier redirect its powers on humans. They escape in Stryker's helicopter, and Pyro, swayed to Magneto, joins them. Nightcrawler teleports Storm inside Cerebro, where she creates a snowstorm to break Jason's concentration and free Xavier. The X-Men flee the dam as water engulfs it, killing Stryker, but their X-Jet loses power and struggles to take off as floodwaters approach. Jean sneaks off, telepathically says goodbye, and holds back the water—raising the jet above it with flames erupting from her body—until she releases and the flood crashes down on her. The X-Men give Stryker's files to the President, with Xavier warning that humans and mutants must unite for peace. At the school, Xavier, Cyclops, and Logan remember Jean as Xavier begins a class. Meanwhile, a Phoenix-like shape rises from flooded Alkali Lake.

FBI Special Agent Sean Archer survives an assassination attempt by Castor Troy, a terrorist-for-hire, but the bullet kills his son Michael. Archer then engages in an extended vendetta against Troy. It culminates, six years later, in his team ambushing Troy, who is with his younger brother and accomplice, Pollux, on a remote desert airstrip. Castor goads Archer by saying he knows of a bomb that is located somewhere in Los Angeles and is set to explode in a few days. Before Archer can learn more, Castor is knocked unconscious and falls into a coma. Pollux, in custody, affirms that the bomb is real but refuses to reveal its location. In secret, Archer reluctantly undergoes a highly experimental face transplant procedure by Dr. Malcolm Walsh to take on Castor's face, voice, and appearance. Archer-as-Castor is taken to the same high-security prison where Pollux is being held in order to obtain information on the bomb's location. Castor unexpectedly awakens from his coma and discovers that his face is missing. He calls his gang, and they force Dr. Walsh to transplant Archer's face onto him. Meanwhile, Archer successfully learns the bomb's location from Pollux before being informed that he has a visitor. Anticipating a reunion with his colleagues and a return to his normal life, Archer instead finds Castor wearing his face. Upon revealing he has murdered everyone else who knows about the face transplant, Castor gleefully informs Archer that he looks forward to ruining his FBI career and ravishing his wife. Pollux is freed when he willingly tells Castor-as-Archer of the bomb's location, and Castor subsequently disarms the bomb. Castor earns admiration from the FBI office and becomes close to Archer's wife Eve and daughter Jamie, whom Archer had been neglecting while seeking to avenge the death of his son. Back at the prison, Archer-as-Castor escapes after staging a riot and retreats to Castor's headquarters. There, he meets Sasha, the sister of Castor's primary drug kingpin Dietrich Hassler, and her son Adam, who reminds him of Michael. Archer discovers that Adam is Castor's son. Castor learns of Archer's escape and hastily assembles a team to raid his headquarters. The raid turns into a bloodbath, and many FBI agents and several members of Castor's gang, including Dietrich and Pollux, are killed. Archer-as-Castor, Sasha, and Adam all manage to escape. In the aftermath of the raid, Archer's supervisor, Director Victor Lazarro, angrily lambasts Castor-as-Archer for the unnecessary bloodshed he caused. Castor, still furious over Pollux's death, murders Lazarro and is subsequently promoted to acting director in his place. Meanwhile, after taking Sasha and Adam to a safe location, Archer-as-Castor approaches Eve and convinces her to test Castor-as-Archer's blood to confirm his identity. After testing the blood and being convinced that the man wearing her husband's face is in fact an imposter, Eve tells Archer that Castor will be vulnerable at Lazarro's funeral. At the ceremony, Castor-as-Archer has taken Eve hostage. Sasha arrives, and a gunfight ensues; Sasha manages to save Eve after taking a bullet. Archer-as-Castor promises a dying Sasha that he will take care of Adam and raise him away from criminal life. Castor briefly takes Jamie hostage, but she escapes by stabbing him with the butterfly knife that he lent her earlier for self-defense. Following the confrontation at the church, Castor reaches the docks and commandeers a speedboat while Archer commandeers one of his own to continue the pursuit. The chase ends when Archer forces Castor to the shore in a collision. With their boats grounded, the two proceed to fight to the death. Upon gaining the upper hand in the struggle, Archer manages to corner Castor at gunpoint with a speargun, only for the latter to prevent him from shooting by grabbing the firing mechanism. While admitting defeat, Castor tries to disfigure his face so that Archer will be doomed to wear the former's face forever. Before he can finish, Archer kicks Castor in the groin, causing him to lose his grip on the gun and allowing Archer to finally kill him. Backup agents arrive and address Archer-as-Castor by his true name, having been convinced by Eve of Archer's identity. After the face transplant surgery is reversed, Archer returns home. He and Eve adopt Adam, keeping Archer's promise to Sasha.

In 2293, the Federation starship Excelsior, commanded by Captain Hikaru Sulu, discovers that the Klingon moon of Praxis has been destroyed in a mining accident. The loss of Praxis and the ecological devastation of the Klingon homeworld throws the Klingon Empire into turmoil. No longer able to afford war with the Federation, the Klingons pursue peace. Starfleet sends the Federation starship Enterprise to meet with the Klingon Chancellor Gorkon and escort him to negotiations on Earth. Enterprise Captain James T. Kirk, whose son David was murdered by Klingons, opposes peace and resents the assignment. Enterprise and Gorkon's battlecruiser rendezvous and continue towards Earth, with the two command crews sharing a tense meal. Later that night, Enterprise appears to fire torpedoes at the Klingon ship, disabling its artificial gravity. During the confusion, two men wearing Starfleet spacesuits and magnetic boots beam aboard the Klingon vessel, kill two crew members, and mortally wound Gorkon before escaping. Kirk surrenders to avoid armed conflict and beams aboard with Doctor Leonard McCoy to try and save Gorkon's life. The chancellor dies, and Gorkon's chief of staff, General Chang, arrests Kirk and McCoy for his assassination. A Klingon court finds the pair guilty and sentences them to life imprisonment on the frozen planetoid Rura Penthe. Gorkon's daughter Azetbur becomes the new chancellor and continues diplomatic negotiations; the conference is relocated for security, and the new location is kept secret. While several senior Starfleet officers want to rescue Kirk and McCoy, the Federation president refuses to risk full-scale war; Azetbur likewise refuses to invade Federation space. Kirk and McCoy arrive at the Rura Penthe mines and are befriended by Martia, a shapeshifter, who offers them an escape route; in reality, it is a ruse to make their arranged deaths appear accidental. Once her betrayal is revealed, Martia transforms into Kirk's double and fights him, but is killed by the prison governor to silence any witnesses. Kirk and McCoy are beamed aboard Enterprise by Spock, who has assumed command and launched an investigation in Kirk's absence. Determining that Enterprise did not fire the torpedoes, the crew searches for the assassins. Kirk and Spock set a trap to draw out the accomplice in sick bay and discover that the killer is Spock's protégé, Valeris. To find the identity of the other conspirators, Spock initiates a forced mind-meld and learns that Federation, Klingon, and Romulan officials conspired to sabotage the peace talks. The torpedoes that struck Gorkon's cruiser came from Chang's ship, which has the unique ability to fire its weapons while cloaked. Enterprise and Excelsior race to Khitomer, the location of the peace talks. Chang's cloaked ship attacks and inflicts heavy damage on Enterprise. At the suggestion of Spock and Uhura, Spock and McCoy modify a torpedo to home in on the exhaust emissions of Chang's ship. The torpedo impact reveals Chang's location, and Enterprise and Excelsior destroy his ship with a volley of torpedoes. The crews from both ships beam to the conference and thwart the assassination attempt on the Federation president's life. Starfleet Command orders Enterprise to return to Earth to be decommissioned. Kirk decides to take his ship on one last cruise instead, and notes in his log a new generation of explorers will continue their legacy.

In the first years of the 21st century a third World War broke out. Those of us who survived knew mankind could never survive a fourth; that our own volatile natures could simply no longer be risked. So we have created a new arm of the law – The Grammaton Cleric, whose sole task is to seek out and eradicate the true source of man's inhumanity to man; his ability to feel. Established by survivors of World War III, the totalitarian city-state of Libria blames human emotion as the root of all conflicts. It strictly outlaws all activities or objects that stimulate emotion, with violators labeled Sense Offenders and sentenced to death. The population has to take a daily injection of the emotion-suppressing drug called Prozium II. Libria is governed by the Tetragrammaton Council, led by "Father", who communicates propaganda through giant video screens. The police force is led by the Grammaton Clerics, elite fighters trained in the art of gun kata. Clerics frequently raid homes to search for and destroy illegal materials – art, literature and music – executing violators on the spot. A resistance movement, known as the "Underground", emerges to topple Father and the Tetragrammaton Council. In 2072, John Preston is a high-ranking Cleric whose wife, Viviana, was executed as a Sense Offender, leaving him as a single parent of two. Following a raid, Preston's partner Errol Partridge saves a book of poems by W. B. Yeats instead of turning it in for incineration. He follows Partridge to the Nether – a term for regions outside the city – and finds him reading the book. Seeing Preston, Partridge claims he gladly pays the price of feeling emotion. Preston executes Partridge. Preston accidentally breaks his last vial of Prozium and is unable to refill them before the next raid. Brief episodes of emotion set in evoking memories, stirring feelings, and making him more aware of his surroundings. He intentionally skips additional doses of Prozium, hiding them behind his bathroom mirror. Partridge is replaced with an ambitious, career-conscious Brandt, who admires Preston's work as a Cleric. On a raid, they arrest Sense Offender Mary O'Brien. Preston prevents Brandt from executing O'Brien, saying she should be interrogated. Preston feels remorse for killing Partridge, develops an emotional relationship with O'Brien, and seeks atonement. He uncovers clues that lead to meeting Jurgen, the Underground leader. Jurgen plans to disrupt Prozium production to spark an uprising and convinces Preston that Father must be assassinated. Vice-Counsel DuPont meets with Preston to reveal that there is a traitor in the upper ranks of the Clerics, and assigns Preston the task of unmasking the traitor. Relieved, Preston accepts and promises to locate the Underground's leadership. When O'Brien is set to be executed, Preston attempts to stop the execution and fails. His memory of his wife's execution triggers an emotional breakdown. Brandt, who has been suspecting Preston of being a Sense Offender, arrests and brings him before DuPont. Preston tricks DuPont into believing that Brandt is the traitor. Preston is told that his home will be searched as a formality. He rushes home to destroy the hidden vials only to discover his son, who stopped taking Prozium after his mother died, already has. Jurgen tells Preston to capture the resistance leaders to regain Father's trust, hoping it will get him close enough to assassinate Father. Preston is granted an exclusive audience with Father only to discover that Brandt was not arrested; it was part of a ruse to capture Preston and the Underground. DuPont reveals he is Father, having secretly replaced the original Father who died, and that his cabal doesn't take Prozium to suppress emotion. He taunts Preston, asking how it felt to betray the Underground. Having anticipated the trap, Preston fights his way through an army of bodyguards to DuPont's office, confronting and killing Brandt in a katana battle. DuPont and Preston engage in a gun kata showdown. Preston wins as DuPont pleads for his life, asking "Is it really worth the price?" Paying homage to Partridge's last words, he responds "I pay it gladly" and kills DuPont to satiate his need for revenge. He destroys the command center that broadcasts Father propaganda. Preston watches with satisfaction from above as the Underground destroys Prozium manufacturing plants, signaling the beginning of the revolution.

In 2286, an enormous cylindrical probe moves through space, sending out an indecipherable signal and disabling the power of every ship 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 all space-faring vessels not to approach Earth. On the planet Vulcan, the former officers of the late USS Enterprise are living in exile. Accompanied by the Vulcan Spock, still recovering from his resurrection, the crew take their captured Klingon Bird of Prey and return to Earth to face trial for their actions. Receiving Starfleet's warning, Spock determines that the probe's signal matches the song of extinct humpback whales and that the object will continue to wreak havoc until its call is answered. The crew uses their ship to travel back in time via a slingshot maneuver around the Sun, planning to return with a whale to answer the alien signal. Arriving in 1986, the crew finds their ship's power drained by the time travel maneuver. Hiding the ship in San Francisco 's Golden Gate Park using its cloaking device, the crew split up to accomplish several tasks: Admiral James T. Kirk and Spock attempt to locate humpback whales, while Montgomery Scott, Leonard McCoy, and Hikaru Sulu construct a tank to hold the whales they need for a return to the 23rd century. Uhura and Pavel Chekov are tasked to find a nuclear reactor, whose energy leakage can be collected and used to regenerate the decaying dilithium crystals. Kirk and Spock discover a pair of humpback whales in the care of Dr. Gillian Taylor at a Sausalito aquarium and learn they will soon be released into the wild. Kirk tells her of his mission and asks for the tracking frequency for the whales, but she refuses to cooperate. Meanwhile, Scott and McCoy trade the formula of transparent aluminum for the materials needed for the whale tank. At the same time, Sulu secures the use of a "Huey" helicopter to transport them. Uhura and Chekov locate a nuclear-powered ship, the aircraft carrier Enterprise. They collect the power they need but are discovered on board. Uhura is beamed out, but Chekov is captured, interrogated (under the assumption he is a Soviet spy), and subsequently severely injured in an escape attempt. Gillian learns the whales have been released early and goes to Kirk for assistance. Gillian, Kirk, and McCoy rescue Chekov from a nearby hospital and return to the now-recharged Bird of Prey. After saving the whales from whalers and transporting them aboard, the crew returns with Gillian to their own time. On approaching Earth, the ship loses power due to the alien probe and crash-lands into the waters of San Francisco Bay. Once released from near-drowning, the whales respond to the probe's signal, causing the object to reverse its effects on Earth and return to the depths of space. Later, the Enterprise crew stand judgment before the Federation Council, which acknowledges the crew's part in saving the planet, and drops all pending charges except the one against Kirk, for disobeying a superior officer. Kirk is demoted to the rank of captain, but as a furtive reward for his heroics, he is returned to the command of a starship. Kirk and Gillian part ways, as she has been assigned to a science vessel by Starfleet. Spock's father Sarek finally accepts his son's earlier choice to enter Starfleet, further mending their broken relationship. The crew discovers they have been awarded the newly christened USS Enterprise (NCC-1701-A), and leaves on a shakedown mission.

In the future, Earth is governed by the United Citizen Federation, a stratocratic regime founded generations earlier by "veterans" after democracy and social scientists brought civilization to the brink of ruin. Citizenship is exclusively earned through federal service, which grants rights—like voting and procreation—that are withheld from ordinary civilians. Humans, who are now capable of interstellar travel, conduct colonization missions throughout the galaxy, bringing them into conflict with a race of highly evolved insectoid creatures dubbed "Arachnids" or, derisively, "bugs". Against his parents' objections, teenage jock Johnny Rico enlists in the Mobile Infantry to remain close to his girlfriend, spaceship pilot Carmen Ibanez. Their psychic friend Carl Jenkins joins military intelligence, while Isabelle "Dizzy" Flores—who is in love with Rico—deliberately transfers to his squad. Carmen ends her relationship with Rico due to their diverging career paths and her growing feelings for a fellow pilot, Zander Barcalow. During training, Rico impresses his drill sergeant, Zim, earning a promotion to squad leader. However, Rico makes a mistake during a training exercise, which leads to the death of a squad member and the resignation of another, resulting in Rico's demotion and flogging. Disheartened, Rico quits, but re-enlists after learning that an asteroid sent by the Arachnids has destroyed Buenos Aires, killing millions, including his parents. An invasion force is deployed to Klendathu, the Arachnids' home planet, but military intelligence underestimates the Arachnids' defensive abilities, leading to hundreds of thousands of human casualties. Badly wounded, Rico is rescued by Lieutenant Jean Rasczak, his former high school teacher, but is mistakenly reported dead, devastating Carmen. Following his recovery, Rico, Dizzy, and squadmate Ace Levy join Rasczak's elite unit, the Roughnecks. After Rico defeats a gigantic "Tanker Bug" on the disputed planet of Tango Urilla, he is elevated to the rank of corporal for his valor and begins a romantic relationship with Dizzy. Responding to a distress signal on the Arachnid-controlled Planet P, the Roughnecks discover an Arachnid-ravaged outpost and are ambushed by the bugs. Carmen and Zander recover the surviving Roughnecks by dropship, but not before Dizzy is fatally impaled by an Arachnid and Rico mercy kills the mutilated Rasczak. The group returns to the fleet assembled in orbit above P, where Dizzy is eulogized. Jenkins, now a colonel, reveals the Roughnecks were deliberately ordered into the trap, justifying it as a necessary sacrifice to confirm the existence of a "Brain Bug", an intelligent Arachnid strategically directing the others. He assigns Rico command of the Roughnecks and field-promotes him to lieutenant, instructing him to return to P and capture the Brain Bug. As the battle commences, Carmen's ship is destroyed by the Arachnids; she and Zander escape in an escape pod, but it crashes into an underground tunnel system. The pair are captured by the Arachnids, and the Brain Bug consumes Zander's brain, killing him and absorbing his knowledge. Rico directs his squad to complete their mission while he, Ace, and their squadmate Watkins rescue Carmen and hold the Arachnids at bay with a miniature nuclear bomb. The Brain Bug escapes while the Arachnids attack and fatally wound Watkins, who sacrifices himself by detonating the bomb while his teammates escape. On the surface, they learn that Zim has captured the Brain Bug and the assembled troops rejoice as Jenkins psychically detects it is afraid. A propaganda broadcast details how the Brain Bug is being invasively studied to learn its secrets and ensure humanity's victory. The ad encourages viewers to enlist and do their part in the war so they can become like Carmen, now captain of her own ship, and Rico, who enthusiastically leads his troops into another battle.

Dr. Jeremy Stone recounts the events before the United States Senate Committee on Space Sciences in 1971: After a U.S. government satellite crashes near the small rural town of Piedmont, New Mexico, on February 5, nearly all the residents are dead. A military recovery team from Vandenberg Air Force Base sent to recover the satellite dies while trying to do so. Suspecting that the satellite has brought back an alien organism, the military activates an elite team of scientists. Dr. Stone, the team leader, and Dr. Mark Hall, a surgeon, are dropped in by helicopter. They discover the town's doctor opened the satellite in his office and that all of his blood has crystallized into a powder, the same death befalling nearly all of the town. Stone and Hall retrieve the satellite and find two survivors, 69-year-old alcoholic Peter Jackson and six-month-old crying infant Manuel Rios. The elite team also includes Dr. Charles Dutton and Dr. Ruth Leavitt, who join them at a top-secret Nevada underground facility, code named Wildfire. They go through four sub-levels of decontamination procedures, arriving at the fifth sub-level laboratories. If the organism threatens to escape, the Wildfire facility includes an automatic nuclear self-destruct mechanism to incinerate all infectious agents. Under the " odd-man hypothesis ", Dr. Hall is entrusted with the only key that can deactivate the device, the theory being that an unmarried male is the most dispassionate person within a group to make critical decisions in a crisis. Examining the satellite, the team discovers the microscopic alien organism that caused the deaths. The greenish, throbbing life form is assigned the code name "Andromeda." Infecting through the lungs, Andromeda kills biological life almost instantly via a blood clot in the brain and asphyxiation. It appears to be highly virulent. The team studies the organism using animal subjects, an electron microscope, and culturing in various growth media to learn how it behaves. The microbe contains the hydrogen and carbon required for terrestrial life and appears to have a crystalline structure, but lacks the DNA, RNA, proteins, and amino acids present in all forms of terrestrial life, and directly transforms energy to matter with no discernible byproducts. Hall tries to determine why the two Piedmont residents survived. Unknown to the others, Leavitt's research on the germ is impaired by her undisclosed epilepsy. A military jet crashes near Piedmont after the pilot radios that his plastic oxygen mask is dissolving. Hall realizes that the alcoholic Jackson survived because his blood was too acidic from drinking Sterno, and that the baby lived due to his blood being too alkaline from constant crying, suggesting that Andromeda can survive only within a narrow range of blood pH. Just as he has this insight, the organism mutates into a non-lethal form that degrades synthetic rubber and plastic. Andromeda escapes the biocontainment room into the laboratory where Dutton is working. When Andromeda causes all the laboratory's seals to start decaying, a five-minute countdown to nuclear destruction is initiated. Hall rescues Leavitt from an epileptic seizure, triggered by the flashing red lights of Wildfire's alarm system. The team discover that the microbe would thrive on the energy of a nuclear explosion and would consequently be transformed into a super-colony that could destroy all life on Earth. Hall races to reach a functioning station where he can disable the nuclear bomb with his key. He endures multiple attacks by automated lasers as he climbs through the laboratory's central core. He finds a working station, disables the bomb with seconds to spare, and collapses. Hall awakens in a hospital. His colleagues reveal that clouds are being seeded over the Pacific Ocean, which will cause rain to sweep Andromeda from the atmosphere and into alkaline seawater, rendering it harmless. Stone finishes testifying by saying that while they were able to defeat the alien pathogen, they may be unable to do so in the future. The film ends with a computer feed suddenly stopping and the computer flashing the number "601", the Wildfire code for information coming in too fast to analyze.

In the future, a totalitarian government will employ a force known as Firemen to seek out and destroy all literature. They can search anyone, anywhere, at any time, and burn any books they find. One of the firemen, Guy Montag, meets one of his neighbors, Clarisse, a young school teacher who may be on the government's radar due to her unorthodox views. The two discuss his job, and she asks whether he ever reads the books he burns. Curious, he begins to hide books in his house and read them, starting with Charles Dickens's David Copperfield. This leads to conflict with his wife, Linda, who is more concerned with being popular enough to be a member of The Family, an interactive television programme that refers to its viewers as "cousins". At the house of an illegal book collector, the fire captain, Beatty, talks with Montag at length about how books make people unhappy and make them want to think that they are better than others, which is considered anti-social. The book collector, an old woman who was seen with Clarisse a few times during Montag's rides to and from work, refuses to leave her house, opting instead to burn herself and the house so that she can die with her books. Returning home that day, Montag tries to tell Linda and her friends about the woman who martyred herself in the name of books and confronts them about knowing anything about what's going on in the world, calling them "zombies" and telling them that they're just "killing time" instead of living life. Disturbed over Montag's behavior, Linda's friends try to leave, but Montag stops them by forcing them to sit and listen to him read a passage from the novel David Copperfield. Montag reads a highly abridged excerpt from chapter 48, beginning with the words "There can be no disparity in marriage like unsuitability of mind and purpose" which describe Dora's death. During the reading, one of Linda's friends breaks down crying, aware of the feelings she repressed over the years, while Linda's other friends leave in disgust over Montag's alleged cruelty and the "sick" content of the novel. That night, Montag dreams of Clarisse as the book collector who killed herself. The same night, Clarisse's house is raided, but she escapes through a trapdoor in the roof, thanks to her uncle. Montag breaks into Beatty's office, looking for information about the missing Clarisse, and is caught but not punished. Montag meets with Clarisse and helps her break back into her house to destroy papers that would bring the Firemen to others like her. She tells him of the "book people", a hidden sect of people who flout the law, each of whom has memorised a book to keep it alive. Later, Montag tells Beatty that he is resigning but is persuaded to go on one more call, which turns out to be Montag's own house. Linda leaves the house, telling Montag that she couldn't live with his book obsession and leaves him to be punished by the Firemen. Angrily, he destroys the bedroom and television before setting fire to the books. Beatty lectures him about the books and pulls a last book from Montag's coat, for which Montag kills him with the flamethrower. He escapes and finds the book people, including Clarisse, where he views his "capture" on television, staged to keep the masses entertained and because the government doesn't want it to be known that he is alive. Montag selects a book to memorise, Tales of Mystery and Imagination by Edgar Allan Poe, and becomes one of the book people.

Sidney Stratton, a gifted research chemist and former Cambridge scholar, is obsessed with developing a fibre that never wears out and resists dirt. His fixation and insistence on costly laboratory facilities lead to repeated dismissals from jobs at several textile mills across Northern England. At Birnley Mills, where he is employed as a labourer, Stratton secretly gains access to research equipment and, through persistence, succeeds in producing a revolutionary synthetic fibre. A suit is tailored from the material: it is brilliantly white, as it cannot absorb dye, and faintly luminous due to traces of radioactive compounds in its structure. At first, Stratton is celebrated as a scientific pioneer. Mill owners recognise the brilliance of his discovery, and the press hails his work as a breakthrough. However, both management and organised labour quickly grasp the broader consequences. If clothing made from the fibre never wears out, the textile trade will collapse once consumers purchase sufficient garments, leaving thousands unemployed and destroying the profitability of the industry. Industrialists attempt to coerce Stratton into relinquishing his formula, while union leaders also pressure him to suppress the invention. Stratton, proud of his achievement and convinced of its benefit to humanity, refuses to compromise. The mill owner's daughter, Daphne Birnley, is enlisted to persuade Stratton to abandon his work in return for a monetary settlement. Though initially willing, she comes to admire his integrity and instead encourages him to make his discovery public. Stratton, however, slowly realises that his creation has no allies: employers, workers, and even acquaintances oppose its release, fearing economic ruin. The film reaches its climax with Stratton pursued through the streets at night, wearing the glowing white suit. Chased by a mob of industrialists and workers, he appears cornered, but suddenly the fabric begins to fail. The chemical structure of the fibre proves unstable, and the suit disintegrates before the crowd's eyes. Triumphant, the mob strips away the remnants, leaving Stratton in his underclothes. Only Daphne and Bertha, a sympathetic mill worker, express pity for his plight. The following morning, Stratton is dismissed from his position at Birnley Mills. As he gathers his belongings, he examines his laboratory notes. A sudden insight strikes him, and he exclaims, "I see!" He departs with renewed determination, suggesting he will resume his quest elsewhere.

As 1999 nears its end, Los Angeles has become a dangerous war zone. A Chinese restaurant is robbed by a group of criminals, with one recording the event with a SQUID (Superconducting QUantum Interference Device), an illegal electronic device that records memories and physical sensations directly from the wearer's cerebral cortex onto a MiniDisc -like storage device. Lenny Nero, a former LAPD officer turned black marketeer of SQUID recordings, buys the robbery clip from his main supplier Tick. Elsewhere, Iris, a prostitute and former friend of Faith Justin (Lenny's ex-girlfriend), is chased by LAPD officers Burton Steckler and Dwayne Engelman. Iris escapes on a subway car, but Engelman pulls off her wig, revealing a SQUID recorder headset. Lenny pines for Faith and relies on emotional support from his two best friends—Max Peltier, a private investigator, and Lornette "Mace" Mason, a bodyguard and limousine driver. Mace has unrequited feelings for Lenny from when he was still a cop and acted as a father figure for her son after her boyfriend was arrested on drug charges, but disapproves of his SQUID-dealing business. While Lenny and Max are drinking at a bar, Iris drops a SQUID disc through the sunroof of Lenny's car before it is towed away. Mace picks Lenny up and takes him to a nightclub where Faith is going to sing. There, Lenny receives a SQUID disc from an anonymous contact and unsuccessfully tries to get Faith away from her new boyfriend, Philo Gant. Philo is a music industry mogul who managed the recently murdered rapper Jeriko One. While in the car with Mace, Lenny plays the disc the contact gave him and watches as Iris is brutally raped and murdered by an attacker at the Sunset Regent hotel. As they approach the hotel, Iris's body is taken out on a stretcher. The next day, they take the disc to Tick, who cannot identify the source of the recording, but recalls that Iris was looking for Lenny. Deducing Iris may have left something in Lenny's car, Mace and Lenny go to the impound and find Iris's disc. Steckler and Engelman appear and demand the disc at gunpoint, but Lenny and Mace escape in her bullet-resistant car before being forced to stop at a dock. Steckler pours gasoline on the car and sets it on fire, but Mace drives it into the harbor, extinguishing the flames. When they reach the surface, the cops have left. Mace takes Lenny to her brother's house, and they watch Iris's disc, showing Iris was with Jeriko One when Steckler and Engelman pulled him over and murdered him, because his anti-police lyrics and activism incited protests against the LAPD. The two return to Tick, who Max explains has been rendered brain-dead from forceful exposure to amplified SQUID signals. Lenny fears Iris's attacker covered his tracks by "killing" Tick and will come after Faith. Back at the nightclub, Lenny and Mace confront Faith, who reveals that Philo is afraid Iris's disc would reveal that he kept his artists under surveillance. Lenny and Mace disagree over whether to trade the disc to Philo for Faith's freedom or release it publicly, which could incite a citywide riot. As midnight approaches, Lenny and Mace sneak into a private party that Philo is hosting at the Westin Bonaventure Hotel for the city's wealthy elite. Lenny has a change of heart and tells Mace to give the disc to deputy police commissioner Palmer Strickland. In Philo's penthouse suite, Lenny finds Philo brain-dead on the floor and another disc, revealing Faith's affair with Max, who "fried" Philo's brain with an amplified recording of them feigning rape. Pointing a gun at Lenny, Max explains that Philo hired him to kill Iris, but when Philo wanted Faith dead as part of the coverup, he decided to frame Lenny for the murders. Lenny and Max struggle in a fight, Faith intervenes and pulls off Max's wig with a SQUID inside - assuring a confession - and Max stabs Lenny in the back. The fight culminates with Lenny on the balcony with Max hanging over; Lenny pulls the knife from his back to cut his necktie and drop Max to his death. Lenny goes downstairs to find Mace, leaving Faith standing alone on the balcony. Meanwhile, on the crowded streets, Mace subdues Steckler and Engelman with baton and taser, but other officers take down Mace. The crowd moves in, in support of Mace, and a major riot seems inevitable. Strickland, who has viewed Iris's disc, arrives and orders Mace's release and the arrest of Steckler and Engelman for murder. Engelman commits suicide; Steckler threatens Mace, but the officers gun him down. Lenny finds Mace, and the two share a hug before she gets in Strickland's car. Then Lenny drags her out, and they share a kiss as the crowd celebrates the turn of the new millennium.

Café owner Kato (Kazunari Tosa) discovers that his computer's monitor shows what will happen two minutes into the future from the perspective of the television in the café, which itself displays what happened two minutes into the past. The computer is brought down to face the television, creating a Droste effect, allowing the characters to see several minutes into the future. Kato's friends and coworkers discover this. Persuaded by a future version of himself, he decides to ask his love interest, Megumi, on a date; she declines, but Kato is forced to pretend to encourage his past self to prevent a paradox. Kato's friends also attempt to take advantage of the time window, getting caught up in a gang rivalry in the process. Kato uses his knowledge of the near future, as well as objects the group obtained throughout the film, to attack the gang members and save Megumi who has been taken upstairs. Returning downstairs, they find that two time cops have sedated everyone except himself and Megumi. The cops try to force the pair to ingest memory-wiping powder, but they sneeze it away, causing the cops to disappear from reality as a result of a paradox. Megumi and Kato sit down and discuss their lives together.

In 2057, the Sun is dying and Earth is freezing. Eight astronauts aboard the starship Icarus II are sent on a last-chance mission to deliver and detonate a colossal stellar bomb intended to reignite the Sun. As the ship passes Mercury, it receives a distress beacon from Icarus I, the earlier mission that had disappeared seven years prior. Despite engineer Mace's objections, Captain Kaneda, acting on a recommendation from physicist Capa, decides to divert course in order to investigate and also to double the mission's success potential should the identical stellar bomb payload on the original ship prove operational as backup. Navigator Trey plots the new route but inadvertently overlooks realigning the ship's heat shields, damaging reflective panels that protect Icarus II from direct sunlight. Pilot Cassie angles the vessel into Mercury's shadow while Kaneda and Capa perform a spacewalk to repair the shield. The operation destroys two of the ship's communications towers, and reflected light incinerates the oxygen garden, reducing air reserves. When the emergency autopilot forces the ship back into its original alignment, Kaneda orders Capa to retreat and completes the final repair himself, moments before a wave of sunlight engulfs and kills him. Trey blames himself for losing Kaneda, and psychologist Searle sedates him after judging him a suicide risk. Now lacking sufficient oxygen to reach the Sun and deploy the bomb, Icarus II docks with Icarus I to salvage resources. Capa, Searle, Mace and communications officer Harvey board the derelict ship while Cassie and biologist Corazon remain on Icarus II with Trey. Although Icarus I appears largely operational, its mainframe has been sabotaged, preventing payload delivery. Mace finds a damaged entry log from Captain Pinbacker, badly burned and insisting their mission defies God, dated to roughly six and a half years earlier. On the observation deck, Searle discovers the charred bodies of the Icarus I crew, who were apparently exposed to unfiltered solar radiation. An explosive decoupling separates the ships and destroys Icarus I' s outer airlock, stranding the boarding team. With only one intact spacesuit and limited insulation, they decide that Capa, despite Harvey's protests, must take the suit because he is the only crew member able to arm the bomb. Searle stays behind to open the airlock, allowing the others to jettison back toward Icarus II using insulation for protection. Harvey misses the airlock and freezes to death, while Capa and Mace make it back. Left alone on Icarus I, Searle returns to the observation deck and exposes himself to unfiltered sunlight, killing himself. Back aboard Icarus II, Corazon calculates that the remaining oxygen will only sustain four people to the Sun. In order to preserve oxygen, the crew votes to have Mace kill Trey, but Trey has already committed suicide. Although the mission now seems possible, the ship's systems still detect five life signs. Capa investigates and finds Pinbacker alive now aboard Icarus II, having boarded during the docking and caused the decoupling. Pinbacker attacks Capa, traps him in an airlock, disables the ship by lifting its mainframes from coolant baths, and kills Corazon. Mace attempts to manually reset the mainframes, and succeeds with two, but the third crushes his leg and traps him in the coolant; freezing, he urges Capa to finish the mission. Capa pierces an interior hatch with a blowtorch and opens an exterior airlock so decompression tears away the obstruction and frees him, allowing him to deploy the payload. The bomb structure separates from Icarus II, and Capa makes a leap towards the payload as the ship is destroyed by solar radiation. Inside the payload, he finds a wounded Cassie, but Pinbacker confronts them again, claiming he has spent years "speaking to God," and subdues Capa; Cassie pulls Capa away, and he tears burned skin from Pinbacker's arm. As the bomb's gravity shifts, Capa reaches the controls and detonates the payload; in his final moments, spacetime distorts and he reaches out to the Sun's surface as it reignites. On Earth, Capa's sister and her children build snowmen on a frozen Sydney Harbour. As they listen to Capa's final transmission, the sun brightens and sunlight begins to shine down on them.