John Connor has been living off the grid in Los Angeles in the years following the death of his mother, Sarah, from leukemia. Although Judgment Day did not occur on August 29, 1997, as expected, John still believes that a war between humans and the machines will occur. Unable to locate John in the past, Skynet sends a new model of the Terminator called the T-X back to July 24, 2004 to kill other members of the Human Resistance. The T-X is more advanced than previous Terminators, and has an endoskeleton with built-in weaponry, a liquid metal exterior similar to the T-1000, and the ability to reprogram other machines. Unlike previous Terminators, its standard appearance is female. The Resistance sends a reprogrammed Terminator (T-850 - Model 101) back in time to protect the T-X's targets including John and his future wife, Kate Brewster.
In 1989, Kevin Flynn, software engineer and the CEO of ENCOM International, disappears. Twenty years later, his son Sam, now ENCOM's primary shareholder, takes little interest in the company beyond playing an annual prank on its board of directors.
The FBI responds to a brief computer outage at their Cyber-Security Division by tracing down top computer hackers, finding several of them have been killed. Taking others into protective custody, the FBI asks New York City Police Department detective John McClane (Bruce Willis) to bring in Matthew "Matt" Farrell (Justin Long), one of the targeted hackers. McClane finally arrives just in time to prevent Farrell from being killed by assassins working for Mai Linh (Maggie Q), a mysterious cyber-terrorist who works for her boss and love interest, Thomas Gabriel (Timothy Olyphant).
In a restaurant in Los Angeles, a man discusses the 1975 film Dog Day Afternoon before walking off, with numerous SWAT officers pointing guns at him and a dishevelled man following him out. They walk to a nearby building with gunmen and hostages strapped with bombs and ball-bearings. One of the gunmen is killed by a sniper; when the hostage is forcibly taken away, the explosives detonate via a proximity trigger, killing her and others. The film then flashes back four days.
In 1969, students Martin Brice and Cosmo are sneakers who hack into computer networks using university equipment, to redistribute conservative funds to various liberal causes. The police burst in and arrest Cosmo while Martin is out getting pizza, and Martin becomes a fugitive.
Dr. Will Caster (Johnny Depp) is a scientist who researches the nature of death and sentience, including artificial intelligence. He and his team work to create a sentient computer; he predicts that such a computer will create a technological singularity, or in his words "Transcendence". His wife Evelyn (Rebecca Hall) is also a scientist and helps him with his work.
The film opens with Jack Stanfield (Harrison Ford) leaving his house, loving wife Beth (Virginia Madsen) and two children, to his job at Landrock Pacific Bank in downtown Seattle. The day goes smoothly until Jack is visited by a collection agency, claiming that he owes $95,000 in debts to their online gambling site. He trusts a colleague to take care of it (as he is convinced of some form of identity theft, which is later found out to be true and used to later set up Jack with a motive for robbing the bank) and goes out for dinner with colleague Harry Romano (Robert Forster) and potential employer, Bill Cox (Paul Bettany). After the meal, Harry leaves in a taxi and Jack gets in his car. Unexpectedly, Cox follows him into the back seat. Cox then goes on to tell Jack that his family is being held hostage at their home to ensure Jack's cooperation. He then points a gun to Jack's head and forces him to drive home.
During a surprise drill of a nuclear attack, many United States Air Force Strategic Missile Wing missileers prove unwilling to turn a required key to launch a missile strike. Such refusals convince John McKittrick (Dabney Coleman) and other systems engineers at NORAD that missile launch control centers must be automated, without human intervention. Control is given to a NORAD supercomputer, WOPR (War Operation Plan Response), programmed to continuously run military simulations and learn over time.
Kevin Flynn (Jeff Bridges) is a software engineer, formerly employed by the computer corporation ENCOM, who now runs an arcade bar called Flynn's. He wrote several video games, but another ENCOM engineer, Ed Dillinger (David Warner), stole them and passed them off as his own, earning himself a series of promotions until reaching Senior Executive VP. Having left the company, Flynn attempts to obtain evidence of Dillinger's actions by hacking the ENCOM mainframe, but is repeatedly stopped by the Master Control Program (MCP), an artificial intelligence written by Dillinger. However, since its inception the MCP has become power-hungry, illegally appropriating business and even government programs and absorbing them to increase its own capacities; it informs Dillinger of its plans to subjugate The Pentagon and the Kremlin, and expresses interest in China with its request for Chinese-translation programs, blackmailing Dillinger into compliance with records of his theft of the games.
Mae Holland est engagée dans le groupe de services technologiques le plus important au monde, appelé Le Cercle. Elle est bientôt encouragée par le créateur, Eamon Bailey, à participer à une expérience où ses choix auront une influence significative sur la vie privée de ses proches et leur liberté individuelle.
At a nuclear plant in Chai Wan, Hong Kong, a hacker causes the coolant pumps to overheat and explode. Not long after in Chicago, the Mercantile Trade Exchange gets hacked, causing soy futures to rise. The Chinese government and the FBI determine that the hack was caused by a Remote Access Tool (RAT). A military officer in China's cyber warfare unit, Captain Chen Dawai (Leehom Wang), is tasked to find the people responsible for the attacks, and enlists the aid of his sister Chen Lien (Tang Wei), a networking engineer. He meets with FBI Agent Carol Barrett (Viola Davis) in Los Angeles and reveals the code in the RAT was written by himself and Nicholas Hathaway (Chris Hemsworth), his college roommate, in their school days years before Hathaway was sent to prison for an unrelated hack. Dawai asks that the FBI arrange for Hathaway to be released from prison, where he is serving a sentence for computer crimes. Hathaway is offered temporary release in exchange for his services.
In 1988, 11-year-old Dade "Zero Cool" Murphy is arrested and charged with crashing 1,507 computer systems in a single day and causing a single-day 7-point drop in the New York Stock Exchange. His family is fined $45,000 for the events and he is banned from using computers or touch-tone telephones until he is 18 years old. Seven years later, Dade (Jonny Lee Miller), is now living with his divorced mother in New York City. On Dade's 18th birthday, he receives a computer and uses social engineering to hack into a local television station's computer network, changing the current TV program to an episode of The Outer Limits. However, Dade's intrusion is countered by another hacker (handle "Acid Burn") on the same network, and they briefly converse, with Dade identifying himself by a new alias: "Crash Override".
Three MIT students – Jonah, Nic, and Haley – are on a road trip to take Haley to California, a decision that's stressing Nic and Haley's relationship. Haley feels Nic is distancing himself from her and Nic explains he doesn't want his muscular dystrophy to hold her back. During their stay in a hotel, Nic and Jonah discover that the hacker NOMAD (who nearly got Jonah and Nic expelled for breaking into MIT servers), has found their location and is taunting them with strange and ominous emails. They track NOMAD to an abandoned house in the middle of Nevada near their path and decide to go after him. After finding nothing in the house, Nic and Jonah hear Haley scream, and run outside to see her be pulled into the sky, before disappearing into a white light themselves.