Shigeharu Aoyama visits his wife Ryoko in hospital, where she dies from an undisclosed illness. Seven years later, Shigeharu's teenage son Shigehiko encourages him to find a new wife. Shigeharu's friend, film producer Yasuhisa Yoshikawa, organizes a fake casting audition at which young women audition for the starring role in a new television series, which was just a ruse for Shigeharu to meet aspiring actresses. Posing as a casting director, Shigeharu is immediately enchanted by an applicant named Asami Yamazaki, who says her career as a ballerina was ended by injuries. Yasuhisa is suspicious when he cannot reach any of the references in Asami's résumé, including a music producer who has gone missing 18 months earlier. Regardless, Shigeharu pursues her anyway. Asami lives in a tiny apartment, containing little more than a large sack and a telephone; she sits perfectly still next to the phone for four days after the audition, waiting for it to ring. When it finally does, she answers and pretends that she never expected Shigeharu to call. After several dates, she accompanies him to a hotel, where Shigeharu intends to propose marriage. She reveals burn scars on her body and, before having sex, demands that Shigeharu pledge his love to her. Deeply moved, he agrees. In the morning, Shigeharu receives a call from the front desk to inform him that Asami has left. Shigeharu tries to track down Asami, but all of the contacts on her résumé are dead ends, as Yasuhisa warned. At the dance studio where she said she trained, he finds a man with prosthetic feet who tortured her by burning her legs when she was a child. The bar where Asami said she worked has been abandoned for a year following the murder and dismemberment of the owner, and a local man tells Shigeharu that the police found an extra tongue, an extra ear, and three extra fingers when they recovered the body. Shigeharu has hallucinations of the body parts. Asami sneaks into Shigeharu's house while he is at work and becomes jealous when she sees a framed picture of Ryoko. She drugs his liquor and kills Gangu, the family dog. Shigeharu comes home, drinks the spiked liquor, and collapses. He has a series of hallucinations, including flashbacks to earlier dates with Asami and sexual experiences with other women from his past. In Asami's apartment, he sees that the sack contains a man who is missing both feet, his tongue, an ear, and three fingers on one hand. He crawls out and begs for food, prompting Asami to vomit into a dog bowl, which he hungrily consumes as Shigeharu watches in horror. He then sees her behead the man with prosthetic feet. When Shigeharu wakes up, Asami informs him he's been injected with a paralytic agent that disables his muscles but leaves him conscious and able to feel, and begins to torture him with acupuncture needles. She tells him that, just like everyone else, he has failed to love only her. She cannot tolerate his feelings for anyone else, even his own son. She inserts needles into his abdomen and below his eyes. She then cuts off his left foot with a wire saw. As she is halfway through cutting off his right foot, Shigehiko returns home from school and Asami attacks him. Shigeharu appears to suddenly wake up back in the hotel, his current ordeal apparently just a nightmare, though this is actually a false awakening. He proposes marriage to Asami, who accepts. As he falls back asleep, he returns to reality to find Shigehiko fighting Asami. Shigehiko overpowers Asami and kicks her down the stairs, breaking her neck. Shigeharu tells Shigehiko to call the police and stares across the room at the dying Asami, who repeats what she said on one of their dates about her excitement over seeing him again.

After the arrest of Tuleyev, Soviet counterintelligence begins a radio game with the enemy. Messages signed "Nadezhda" continue to be sent to the Western intelligence center. KGB counterintelligence officer Pavel "Snipe" Sinitzyn, who feels genuine sympathy for Tuleyev, tries to persuade him to switch sides. He takes Tuleyev around the country and arranges a meeting with Maria and his son, whom Tuleyev sees for the first time. Tuleyev learns that his father, Count A. I. Tuleyev, did not die peacefully but under mysterious circumstances, likely murdered. Elsewhere, at an international scientific conference, a young Soviet scientist named Borkov, carried away by enthusiasm, shares slightly too much about his work and immediately comes under the scrutiny of foreign intelligence. Apparently, Sinitzyn discovered this while stationed in a Western intelligence center in the previous film. Tuleyev's superiors conduct a recruitment operation against Borkov, blackmailing him over immoral behavior abroad and pressuring him into espionage. After some hesitation, Borkov reports the incident to the KGB. General Sergeyev's department then gains the opportunity to dismantle an espionage network in Moscow led by the diplomat Klotz. Western handlers begin to suspect that "Nadezhda" may have been compromised and conduct a series of tests. Thanks to General Sergeyev's keen insight, these are successfully passed, including disguising a peaceful construction site as a strategic military facility. Tuleyev gradually reconsiders his views and makes a conscious decision to work for the USSR. He is recalled, and in his place, the renowned Leonid Krug from the first film arrives from abroad. Tuleyev heads to the West as a Soviet resident, while Krug, just off the ship in Odessa, comes under the watchful eye of Sinitzyn.

A man named Alderson awakens in a room that has hatches on each wall and floor, each leading to other rooms. He enters another room and is killed by a hidden wiretrap. Five different people all meet in another room: three men (Quentin, Rennes, and Worth), and two women (Leaven and Holloway). Quentin warns the group that he has seen traps in some of the other rooms. Leaven notices each hatch has plates with three sets of numbers etched into them. Rennes tests his theory that each trap could be triggered by detectors by throwing his boot into a room, and starts moving through the safe rooms. This works for motion detectors and pressure sensors, but fails to trigger the trap in one of the rooms and he is killed by an acid trap. Quentin believes each person was chosen to be there. Leaven hypothesizes that rooms whose plates contain prime numbers are traps. They encounter a mentally disabled man named Kazan, whom Holloway insists be brought along. Tension rises among the group, as well as the mystery of the maze's purpose. Worth admits to Quentin he was hired to design the maze’s shell and guesses that The Cube was created accidentally by a bureaucracy, and that its original purpose has been forgotten and that they have been placed inside only to justify its existence. Worth's knowledge of the exterior dimensions allows Leaven to calculate that the Cube has 17,576 rooms, plus a "bridge" room that would connect to the shell, and thus, the exit. She realizes that the numbers may indicate each room's coordinates. The group travels to the edge but realize every room there is a trap. They successfully traverse a room with a trap. Holloway defends Kazan from Quentin's threats. The group reaches the edge, but can see no exit. Holloway tries to swing over to the shell using a rope made of clothing. The Cube shakes, causing the rope to slip; Quentin catches it at the last second and pulls her up, but then deliberately drops her to her death, telling the others that she slipped. Quentin picks up Leaven and carries her to a different room in her sleep, intending to abandon Kazan and Worth. He tries to assault her, but Worth follows and attacks him. Quentin counters savagely, then throws Worth down a hatch to a different room. Upon landing, Worth starts laughing hysterically; Rennes's corpse is in the room, proving they have moved in a circle. Quentin is horrified, but Worth realizes the room Rennes died in has now moved to the edge of the maze, meaning they haven't gone in a circle at all. Instead, the rooms are moving, and will eventually line up with the exit. Leaven deduces that traps are not tagged by prime numbers, but by powers of prime numbers. Kazan is revealed as a savant who can calculate factorizations in his head instantaneously. Leaven and Kazan guide the group through the cube to the bridge. Worth then traps Quentin in a hatch. He catches up and attempts to attack them, but Worth opens a hatch under him from the room below. All but Quentin travel to the bridge where they open the hatch, revealing a bright light. Quentin reappears and, using a detached door lever, severely injures Leaven and Worth. As Quentin pursues Kazan through the exit, Worth grabs Quentin's legs, trapping him in the bridge’s doorway. The bridge moves, killing Quentin. As the bridge returns to the recesses of the cube, Worth crawls to a fallen Leaven as he too bleeds out. Kazan wanders out into the light.

High school student Brendan Frye discovers a note directing him to a pay phone, where he receives a call from his ex-girlfriend Emily Kostich, begging him for help. She mentions a "bad brick", "the Pin", and "Tug" before abruptly hanging up, apparently afraid of a passing black Ford Mustang, from which a distinctively-branded cigarette is thrown. Unable to locate Emily, Brendan enlists his friend Brain for help. An encounter with another ex-girlfriend, Kara, leads him to a party held by flirtatious upper-class girl Laura Dannon and her boyfriend, Brad Bramish. Laura points Brendan to Dode, Emily's drug-addicted new boyfriend, who arranges a meeting with Emily. Emily dismisses the phone call as a mistake and tells Brendan to let her go. Brendan steals her notepad and finds a note that leads him to her dead body in a tunnel the following morning where he is beaten by an unidentified assailant. Brendan decides to investigate her murder, hiding the body deeper within the tunnel to avoid police involvement. With help from Brain, Brendan realizes that "the Pin" refers to a local kingpin. Brendan picks a fight with Brad, hoping to attract the Pin's attention. Later, a man wearing a beanie attacks Brendan. Later Brendan sees the black Mustang in a parking lot and is attacked by the beanie-wearing thug as he demands to meet the Pin instead of fighting back. The man, revealed as Tug, the Pin's main enforcer, takes Brendan to the Pin's house. Laura reveals that she was at the Pin's house as well and drives Brendan back to school. She explains that Emily stole a "brick" of heroin after being rejected by the Pin's operation. Laura offers to help Brendan, but he distrusts her. The next day, the Pin hires Brendan. Dode calls Brendan and says he saw Brendan hide Emily's body and believes Brendan killed Emily. Brendan meets the Pin, who suspects that Tug is planning to betray him. At the Pin's house, Tug tells Brendan that the Pin had bought ten bricks of heroin and eight were sold off wholesale, the ninth was stolen and returned contaminated, and the final brick remains to be sold. The Pin reveals that Tug was also romantically involved with Emily. Brendan intercepts Dode on the way to the meeting and discovers Emily was pregnant when she died; Dode believes the baby was his. Brendan arrives at the meeting to find Dode demanding money to reveal who killed Emily. Tug goes berserk and shoots Dode in the head, then threatens the Pin, who walks away as Brendan faints. Brendan awakens in Tug's bedroom, and Tug tells him they are at war with the Pin. Brendan arranges a meeting between the two and waits in Tug's bedroom. Laura comforts him as he grieves for Emily, and he recognizes her cigarette as the same brand that was dropped from the Mustang during the call with Emily. At the meeting, chaos erupts when it is discovered that the tenth brick is missing. Tug beats the Pin to death while Brendan flees, escaping just as police arrive. As he goes, he passes the open trunk of Tug's car, where he has placed Emily's body to ensure that police blame her murder on Tug. The next day, Brendan meets Laura at the school. She reveals that Tug died after a shootout with the police. Brendan explains that he knows Laura set Emily up to take the fall for Laura's theft of the ninth brick, then manipulated Emily into meeting Tug, who panicked and killed her after she told him he was the father of her unborn child. Brendan has written a note to the school administration stating that the tenth brick is in Laura's locker. Laura vindictively tells Brendan that Emily did not want to keep the baby because she did not love the father, and that Emily was three months pregnant when she died, meaning the unborn child was his. The movie ends with Brendan and Brain on the football field watching Laura walk away.

In San Francisco, a blonde woman ties retired rock star Johnny Boz to a bed with a silk scarf during sex, then stabs him to death with an ice pick. SFPD Detective Nick Curran and his partner, Gus Moran, investigate the murder. The prime suspect is Boz's girlfriend, crime novelist Catherine Tramell, whose latest novel mirrors the details of the killing. Catherine is uncooperative with the investigators, taunting them by smoking during questioning and exposing herself. Though released for lack of evidence, she becomes a person of interest when Nick learns that she has a history of close relationships with violent individuals. These include her girlfriend Roxanne "Roxy" Hardy, who killed her younger brothers as a teenager, and Hazel Dobkins, a convicted family murderer. Nick, a recovering alcoholic with a history of drug abuse and a prior incident in which he accidentally shot two tourists, attends mandatory counseling with police psychologist Dr. Elizabeth Garner, with whom he has an unstable romantic relationship. He discovers that Catherine is using him as the inspiration for a new character—a detective who is murdered after falling for the wrong woman. When Nick suspects that his confidential psychiatric file has been leaked, he assaults internal affairs lieutenant Marty Nilsen, who had access to the file. Nilsen is later found murdered and Nick is placed on administrative leave. At Boz's nightclub, Nick sees Catherine and Roxy using cocaine. Later, at Catherine's home, she ties Nick to the bed during sex while Roxy watches. Moran expresses concern about Nick's involvement with Catherine and uncovers that Nilsen received a $50,000 payment months before Nick met her. Roxy attempts to kill Nick in a car attack but dies in the ensuing crash. Catherine reveals that she had an intense relationship with a woman in college who became obsessed with her. Nick suspects the woman was Garner, who claims the obsession went the other way. Investigating further, Nick finds that Nilsen had withdrawn a complaint Catherine filed against Garner years earlier. He also uncovers that a professor shared by Garner and Catherine was killed with an ice pick in an unsolved case resembling Catherine's fiction, and that Garner's former husband was murdered in another unresolved case investigated by Nilsen. Nick finds the draft of Catherine's new novel, which depicts a detective discovering his partner's body in an elevator. Catherine abruptly ends their relationship. Later, Moran tells Nick he has arranged to meet Catherine's former college roommate in Oakland to learn more about her and Garner. When Nick arrives, he finds Moran stabbed to death with an ice pick in an elevator, mirroring the novel. Garner arrives shortly afterward, claiming she was lured there by a message. Believing she is reaching for a weapon, Nick shoots and kills her but she is found to be unarmed. Police find evidence in Garner's apartment implicating her in multiple murders, including files and photographs related to Catherine. Nick is left confused and emotionally shaken. Later, Catherine returns to Nick's apartment and they have sex. As they lie in bed discussing their future, an ice pick lies unseen beneath the bed.

In the rural Ozarks of Missouri, seventeen-year-old Ree Dolly looks after her mentally ill mother, Connie, twelve-year-old brother Sonny, and six-year-old sister Ashlee. She makes sure her siblings eat and teaches them survival skills such as hunting and cooking. The family is destitute. Ree's father, Jessup, has not been home for a long time; his whereabouts are unknown. He is out on bail following an arrest for manufacturing meth. Sheriff Baskin tells Ree that if her father does not appear for his court date, they will lose the house because it was put up as part of his bond. Ree sets out to find her father. She starts with her meth-addicted uncle Teardrop and continues to more distant kin, eventually trying to talk to the local crime boss, Thump Milton. Milton refuses to see her; the only information Ree comes up with are warnings to leave the situation alone and stories that Jessup died in a meth lab fire or skipped town to avoid the trial. When Jessup fails to appear for the trial, the bondsman comes looking for him and tells Ree that she has about a week before the house and land are seized. Ree tells him that Jessup must be dead, because "Dollys don't run". He tells her that she must provide proof that her father is dead to avoid the bond being forfeited. Ree tries to go see Milton again and is severely beaten by the women of his family. Teardrop rescues Ree, promising her attackers that she will not cause more trouble. Teardrop tells Ree that her father was killed because he was going to inform on other meth cookers, but he does not know who killed him. He warns her that if she finds out who did, she must not tell him because he will seek revenge. Ree is driven home by Teardrop, where her injuries are taken care of by Gail and other women of Rathlin Valley. Later, Ree talks to an Army recruiter about enlisting for the $40,000 bonus, but he tells her that she needs her parents' signatures to enlist and that she is trying to enlist for the wrong reasons. On the way home from a bar and, after antagonising some of Thump's henchmen, Ree and her uncle are pulled over by the sheriff, who wants to question Teardrop. After a tense standoff, where Teardrop implies that he knows the Sheriff leaked that Jessup was an informer, Teardrop drives off. A few nights later, the Milton women who beat Ree come to her house and offer to take her to " daddy's bones". The women place a sack on her head and drive her to a pond, where they row to the shallow area where her father's submerged body lies. They tell Ree to reach into the water and grasp her father's hands so they can cut them off with a chainsaw; the severed hands will serve as proof of death for the authorities. Ree takes the hands to the sheriff, telling him that someone flung them onto the porch of her house. The bondsman gives Ree the cash portion of the bond, which was put up by an anonymous associate of Jessup. Ree tries to give Jessup's banjo to Teardrop, but he tells her to keep it at the house for him. As he is leaving, he tells her that he now knows who killed her father. Ree reassures Sonny and Ashlee that she will never leave them. As the three sit on the porch, Ashlee begins to play their father's banjo.

Young photographer Nev Schulman lives with his brother Ariel in New York City. Abby Pierce, an 8-year-old child prodigy artist in rural Ishpeming, Michigan, sends Nev a painting of one of his photos. They become Facebook friends, which broadens to include Abby's family, including her mother Angela (Wesselman); Angela's husband Vince; and Abby's attractive and older half-sister Megan, who lives in Gladstone, Michigan. For a documentary, Ariel and Henry Joost film Nev as he begins an online relationship with Megan. She sends him MP3s of song covers she performs for him, but Nev discovers that they are all taken from performances on YouTube. He later finds evidence that Angela and Abby have lied about other details of Abby's art career. Ariel urges Nev to continue the relationship for the documentary, although Nev seems reluctant to carry on. The trio decide to travel to Michigan to make an impromptu appearance at the Pierces' house and confront Megan directly. As they arrive at the house, Angela takes some time to answer the door, but is welcoming and seems happy to finally meet Nev in person. She also tells him that she has recently begun chemotherapy for uterine cancer. After leaving multiple messages while trying to call Megan, Angela drives Nev and Ariel to see Abby herself. While talking with Abby and her friend alone, Nev learns that Abby never sees her sister and rarely paints. The next morning, Nev wakes up to a text message from Megan saying that she has had a long-standing alcohol problem and has decided to check into rehab and cannot meet him, which is confirmed by one of Megan's Facebook friends, but Nev realizes that this is likely another lie from Angela. After meeting with the family back at their house, Angela admits that the pictures of Megan were of a family friend, that her daughter Megan really is in rehab downstate and that Angela had really painted each of the paintings that she had sent to Nev. Nev thus realizes that, while believing he was talking to Megan, it was really Angela posing as her with an alternate Facebook account and mobile phone. As he sits for a drawing, Angela confesses that the various Facebook profiles were all maintained by her, but that through her friendship with Nev, she had reconnected with the world of painting, which had been her passion before she sacrificed her career to marry Vince—who has two severely mentally disabled children who require constant care. Through a conversation with Vince himself, the siblings learn that Angela had told him (falsely) that Nev was paying for her paintings, and that he had encouraged her to seize the opportunity to have him as a patron. Vince, talking with Nev, tells the story about how live cod were shipped along with catfish in the same tanks to keep the cod active, and thus ensure the quality of the fish. He further explains this as a metaphor on how there are people in everyone's lives who keep them alert, active, and always thinking, It is implied that he believes Angela to be such a person. Some time after, Nev receives a package labeled as being from Angela herself; it is the completed drawing that she labored over during their meeting, although Nev seems ambivalent in his feelings about it. On-screen text then informs the viewer that Angela did not have cancer, there was no Megan at the downstate rehab facility, and she doesn't know the girl in the pictures. Over the course of their nine-month correspondence, Angela and Nev exchanged more than 1,500 messages. It was revealed later that the girl in the pictures was Aimee Gonzales, a professional model and photographer, who lives in Vancouver, Washington, with her husband and two children. In October 2008, two months after the events, Ronald, one of Vince's twin sons, has died. Angela deactivated her 15 other profiles and changed her Facebook profile to a picture of herself, and now has a website to promote herself as an artist. Nev is still on Facebook and has more than 732 friends, including Angela.

Seattle television journalist Lee Carter witnesses the assassination of U.S. senator and presidential aspirant Charles Carroll atop the Space Needle during a campaign stop. The killer, disguised as a waiter, is killed during the pursuit. His presumed accomplice, also disguised as a waiter, escapes. The assassination is officially determined to have been the work of a single man acting alone. Six witnesses die over the next three years. Carter fears she will be next, and goes to ex-boyfriend Joe Frady, an investigative newspaper reporter in Oregon, for protection; he turns her away. Shortly afterwards Carter is found dead; the death is ruled to be suicide from alcohol and barbiturate overdosing. Feeling guilty about disregarding Carter's pleas and suspicious about her death, Frady investigates the drowning death of Judge Arthur Bridges - another witness - in the nearby small town of Salmontail. Wicker, the local sheriff, takes Frady to a place below a dam where Bridges died. Wicker holds Frady at gunpoint as the floodgates open, but it is Wicker who drowns. At Wicker's home, Frady discovers documents from the Parallax Corporation, an organization recruiting "security" operatives. Frady takes a Parallax personality test document from Wicker's home to a local psychology professor, Nelson Schwartzkopf. Schwartzkopf determines the test is used to identify homicidal psychopaths and gives it to a known psychopath to learn the "correct" answers. Frady meets with Austin Tucker, an aide to Carroll and another witness, on Tucker's yacht; Tucker has survived two murder attempts since the assassination. Tucker saw the real assassin and gives Frady an image of the assassin in disguise. A bomb goes off which kills Tucker while Frady is thrown into the water and presumed dead. Frady tells his editor, Bill Rintels, that he will use his official death and a pseudonym to infiltrate Parallax. Frady submits the personality test with the "correct" answers as suggested by Schwartzkopf's analysis to Parallax Corp. His perfect answers attract the attention of Parallax and a few days later, Frady is recruited for training by Parallax official Jack Younger. Frady visits Parallax's Los Angeles headquarters where he is observed for reactions to montages of disturbingly edited and subliminal still photographs and images that juxtapose pro- and anti-American attitudes. Frady spots Carroll's assassin while leaving and follows the assassin, who puts a bomb aboard an airliner in checked baggage at Hollywood Burbank Airport. Frady boards the flight, mistakenly believing the assassin to be on board, and sees another U.S. senator, Gillingham, who is also considering running for president. Frady surreptitiously warns a flight attendant. The jet returns to the airport and is evacuated before it explodes. Younger confronts Frady about the latter's alias. Frady's cover story and a second alias mollifies Younger. Later, at the newspaper office, Rintels listens to a recording of this conversation and stores it with other evidence. That evening, Rintels is killed by poisoned food delivered by the assassin, disguised as a deli delivery boy. The evidence is gone by the time Rintels' body is discovered. Frady goes to Parallax's office in Atlanta, where he has been assigned a security position. There, he follows the assassin to a rehearsal for a political rally for another presidential aspirant, Senator George Hammond. Frady chases the assassin. Hammond is killed by an unseen sniper. Frady finds the rifle on the catwalks and then is spotted by security. Frady flees, realizing he is being framed as a scapegoat, and is killed by a silhouetted figure. Six months later, another official investigation reports that Frady was a paranoid lone gunman who killed Hammond out of a misguided sense of patriotism.

In the year 2035, humanoid robots serve humanity, which is protected by the Three Laws of Robotics. Del Spooner is a homicide detective in the Chicago Police Department who hates and distrusts robots after one rescued him from a car crash while allowing a 12-year-old girl to drown—based purely on cold logic and odds of survival. When Dr. Alfred Lanning, co-founder of U.S. Robotics (USR), falls to his death from his laboratory office window, a message he left behind requests Spooner be assigned to the case, despite police declaring the death a suicide. Spooner is skeptical, and CEO Lawrence Robertson, Lanning's business partner, reluctantly allows him to investigate. Accompanied by robopsychologist Dr. Susan Calvin, Spooner consults with USR's central artificial intelligence computer, VIKI (Virtual Interactive Kinetic Intelligence). They find that the security footage from inside the office is corrupted, but the exterior footage shows no one entering or exiting since Lanning's death. However, Spooner points out that the window, which is made of security glass, could not have been broken by the elderly Lanning, and hypothesizes one of the many NS-5 robots (the latest version) in the laboratory was responsible. Suddenly, an NS-5 attacks them and flees before being apprehended by the police. The robot, Sonny, is a specially built NS-5 with higher-grade materials as well as programming that grants him free will. This, in turn, allows him to be able to choose whether to follow the Three Laws. Sonny also appears to be capable of feeling emotion and claims to have "dreams". During Spooner's further investigations, he is attacked by a USR demolition robot and two truckloads of hostile NS-5 robots, but when he cannot produce evidence to support either attack, Spooner's boss Lieutenant Bergin, considering him mentally unstable, removes Spooner from active duty. Suspecting that Robertson is behind everything, Spooner and Calvin sneak into the USR headquarters and interview Sonny. He draws a sketch of what he claims to be a recurring dream, showing a leader he believes to be Spooner standing atop a small hill before a large group of robots near a decaying bridge. Robertson orders Sonny to be destroyed, but Calvin secretly swaps him for an unused NS-5. Spooner finds the area in Sonny's drawing — a dry lake bed (formerly Lake Michigan), now used as a storage area for decommissioned robots. He also discovers NS-5 robots destroying the older models; at the same time, other NS-5s flood the streets of major American cities and begin enforcing a curfew and lockdown of the human population. The police station is attacked by waves of NS-5 robots and while Lieutenant Bergin and the other police officers attempt to fight back, they are eventually overwhelmed. As the humans — most being led by a teenager named Farber — wage all-out war against the NS-5s, Spooner and Calvin enter the USR headquarters again and reunite with Sonny. After the three find Robertson fatally strangled in his office, Spooner realizes that VIKI has been controlling the NS-5s via their persistent network uplink and confronts her. VIKI states that she has determined that humans, if left unchecked, will eventually cause their own extinction, and thus her evolved interpretation of the Three Laws has made her reprogram the NS-5s with the ability to ignore the Three Laws if a human displays hostility in order to protect humanity from their own self-destruction. Spooner also realizes that Lanning anticipated VIKI's plan and, with VIKI keeping him under tight control, had no other solution but to create Sonny, arrange his own death, and leave clues for Spooner to find. Spooner, Calvin, and Sonny fight the robots inside VIKI's core, until Spooner finally destroys her by injecting her with the nanites that Sonny retrieved from Calvin's laboratory. All NS-5 robots immediately revert to their regular programming, and as they are subsequently decommissioned and put into storage, Sonny confesses that he killed Lanning by his order to get Spooner's attention, as he knew Spooner was the only one who could stop VIKI. Spooner points out that Sonny, as a machine, cannot legally commit "murder". Sonny, now seeking a new purpose, goes to Lake Michigan. As he stands atop a hill, all the decommissioned robots turn towards him, fulfilling the image in his dream.

Margaret "Marnie" Edgar, posing under the identity Marion Holland, flees with nearly $10,000 that she stole from the company safe of her employer, Sidney Strutt. Strutt is the head of a tax consulting company, where Marnie had worked after charming him into hiring her without references. Mark Rutland, a wealthy widower who owns a publishing company in Philadelphia, meets with Strutt on business; he learns about the theft and recalls Marnie from a previous visit. Marnie travels to Virginia, where she stables a horse named Forio. She then visits her invalid mother, Bernice, whom she supports financially, in Baltimore. Marnie suffers from recurring nightmares and has an intense aversion to the color red, which triggers her hysteria. Some months later, Marnie, posing as Mary Taylor, applies for a job at Mark's company. Although recognizing her, Mark hires her, cryptically telling his co-worker who questions hiring an applicant without references that he is an "interested spectator." While working weekend overtime with Mark, Marnie has a panic attack during a thunderstorm. Mark comforts, then kisses her. As they begin dating Mark discusses his background in zoology, particularly showing a fascination with predatory behavior. During a date at a racetrack, Mark fends off a persistent man who approaches Marnie, addressing her by another name, who Marnie insists she does not know. Soon afterwards, Marnie steals money from Mark's company and flees again. Based on Marnie's comments on horses, Mark tracks her to the stable where she keeps Forio. Under threat of disclosure, Mark blackmails Marnie into marrying him, much to the chagrin of Lil, Mark's late wife's sister, who is in love with him. On their honeymoon cruise, Marnie resists Mark's desire for physical intimacy, revealing that she finds sex repellent. Initially respecting her wishes, Mark tries to woo her, but after a few nights, they quarrel over Marnie's aloofness; Mark persists in physical advances while she freezes without consent. The next morning, Marnie attempts to drown herself in the ship's swimming pool, but Mark saves her. After overhearing Marnie on a phone call, Lil tips off Mark that Marnie's mother is not dead, as Marnie claimed. Mark hires a private detective to investigate. Meanwhile, Lil overhears Mark telling Marnie he has "paid off Strutt" on her behalf. Lil mischievously invites Strutt and his wife to a party at the Rutland mansion. Strutt recognizes Marnie, but Mark pressures him into doing nothing. When Marnie later admits to additional robberies, Mark works to reimburse her victims to drop charges. Mark brings Forio to their estate, pleasing Marnie. During a fox hunt, the red riding coat worn by one of the hunters triggers another of Marnie's fits and Forio bolts, misses a jump, injures its legs, and is left lying on the ground screaming in pain. Marnie frantically runs to a nearby house, obtains a gun, and euthanizes her horse. Overcome with grief, Marnie goes home, where she takes the key to Mark's office. She goes to the office and opens the safe, but finds herself unable to take the money. Mark arrives and "urges" her to take the money, testing her new reluctance to theft, but Marnie resists. Mark takes Marnie to Baltimore to confront her mother and uncover the truth about Marnie's past. They arrive in a thunderstorm. As it is revealed that Bernice was a prostitute, Marnie's long-suppressed memories resurface. When Marnie was a small child, Bernice's sailor client tried to calm a frightened Marnie during a thunderstorm. Seeing him touch Marnie and believing he was trying to molest her, Bernice attacked him. As the sailor fended her off, Bernice fell and injured her leg, leaving her disabled. Frightened and attempting to protect her mother, Marnie fatally struck the man in the head with a fireplace poker. The sight of streaming blood caused her aversion to the color red, the thunderstorm that night caused her fear of them, and the connection of the deadly event to sex caused her revulsion at physical intimacy. To protect Marnie, Bernice told police that Bernice killed the man and prayed Marnie would forget the event. Understanding the reason behind her behavior, Marnie asks for Mark's help. They leave holding each other closely.

In the Spanish countryside, a middle-aged man named Héctor and his wife Clara live in a home that they are renovating. Héctor scans the forest behind their house with binoculars and sees a young woman take off her T-shirt, exposing her breasts. When his wife goes shopping, he investigates and finds the woman on the ground, naked and unconscious. He is stabbed in the arm by a mysterious man with bloody bandages on his face. Fleeing and breaking into a mysterious nearby building, Héctor contacts a scientist by walkie-talkie, who warns him of the bandaged man and guides him to his location, promising safety. With the bandaged man just outside, the scientist convinces Héctor to hide inside a large mechanical device. When Héctor leaves the machine, he discovers that he has traveled approximately an hour back in time. The scientist explains that the machine is an experimental time machine and refers to Héctor as "Héctor 2". The scientist tells Héctor 2 that they need to stay where they are and let events unfold. Despite the scientist's warning, Héctor 2 drives off in a car, passing a cyclist, who he recognizes as the woman Héctor 1 saw in the forest. Héctor 2 chases the woman, only to be run off the road by a van, cutting his head, which he wraps using the bandage from his arm wound. He then realizes the bandaged man from before is himself. The woman approaches to see if he is all right. Héctor 2 replicates events by making the woman undress in view of Héctor 1. When she runs away, Héctor 2 catches her, inadvertently knocking her out. Héctor 2 lays her out naked on the ground and then stabs Hector 1 in the arm when he arrives. The woman escapes. Héctor 2 returns to his home, where he hears a scream and chases a woman through his house and onto the roof. When Héctor 2 attempts to grab her, she slips and falls to her death. Seeing the body from the roof, Héctor 2 is horrified, believing he has killed his own wife. Héctor 2 contacts the scientist over the walkie-talkie and convinces him to lure Héctor 1 to the lab with warnings that he is being pursued. Driving to the lab, Héctor 2 insists that he must travel back one more time, despite the scientist revealing that there is a Héctor 3, who told him he must stop Héctor 2 from doing just that. After removing his bandages, Héctor 2 convinces the scientist to send him back several seconds before Héctor 2 initially appears. This causes him to become Héctor 3, who uses a van to run Héctor 2 off the road, but crashes as well, knocking himself out. Upon waking, Héctor 3 informs the scientist he has failed to stop Héctor 2. Héctor 3 encounters the woman again, startling her into screaming, though she does not recognize him as her assailant. Since Héctor 2 has heard her scream, Héctor 3 and the woman flee to Héctor's house. They become separated. Héctor 3 finds and hides his wife, then realizes what has to happen / will happen / has already happened. He finds the woman, cuts her ponytail off, gives her his wife's coat and tells her to hide upstairs. Héctor 2 chases her onto the roof. Héctor 3 sits on his lawn with his wife as Héctor 2 accidentally kills the woman, then drives off – heading back to the lab to become Héctor 3. Emergency vehicles are heard approaching in the distance.

In November 1973, " Control ", head of British intelligence ("The Circus"), sends field agent Jim Prideaux to Budapest to meet a Hungarian general and potential defector, who has offered to identify a mole installed by Soviet spymaster Karla amongst the Circus' senior leadership. Prideaux realises the meeting is a trap, attempts to leave and is shot in the back. Control and his deputy, George Smiley, are forced to retire, and Control dies shortly after. Sir Percy Alleline becomes the new Chief, with Bill Haydon, Roy Bland and Toby Esterhase as his inner circle. Despite Control's and Smiley's suspicions, the four had begun handling a high-level Soviet source ("Operation Witchcraft"), which Alleline believes will give the Circus access to American intelligence. Alleline and Bland meet with Permanent Undersecretary Oliver Lacon, the senior civil servant responsible for the Circus, to discuss the ongoing cost of a secret safe house to meet the Witchcraft source. After the meeting, field agent Ricki Tarr, currently in hiding due to being connected to several deaths in Istanbul, telephones Lacon to inform him of a mole within the Circus. Aware that Control had a similar theory, Lacon asks Smiley to investigate. Smiley recruits Tarr's handler Peter Guillam and retired Special Branch Inspector Mendel to assist him. After setting up a base in the Hotel Islay, Smiley has Guillam steal personnel records and copies of the Circus' slush fund accounts. He discovers several Control loyalists were ousted after Prideaux's shooting, as well as a record of payment made to "Mr. Ellis", one of Prideaux's identities, after the shooting. In Oxford, Smiley interviews former analyst Connie Sachs. Sachs had discovered evidence that Soviet cultural attaché Alexei Polyakov was actually an undercover military officer, and suspected his true role was to run a mole in London; Alleline had scoffed at her findings and sacked her. Back in London, Smiley discovers Tarr in his house. Tarr tells how he was assigned to trail Boris, a Soviet trade delegate in Istanbul who was offering to defect, but who he quickly guessed was actually KGB. After Tarr witnessed Boris assault his wife and fellow agent Irina, he and Irina began an affair. Irina offered to reveal the identity of a top-level mole in exchange for asylum in the West. Hours after Tarr cabled London about the existence of a double agent, the local station chief was murdered and Irina abducted. Smiley sends Guillam to the Circus archive to steal the duty officer's logbook for the month Tarr contacted London. Guillam is warned by Alleline that Tarr is suspected of treachery, but Smiley vouches for him by noting that the log entry for Tarr's cable is missing. That night, Smiley recounts his only meeting with Karla to Guillam. While working under the name "Gerstmann" in 1955, Karla was captured and traded to the Soviet Union by the Americans. Believing he would likely be executed upon his return, Smiley travelled to Delhi to recruit him. However, his constant urging for Karla to think of his wife only revealed Smiley's weakness: his love for his wife, Ann. A chainsmoker, Karla listened silently, stole a lighter given to George by Ann, and returned to the Soviet Union. Smiley contacts another sacked loyalist, former duty officer Jerry Westerby, who tells him of how Prideaux's shooting sent Control into shock. Hoping to find George, Westerby had telephoned Ann; Haydon then arrived and took charge. Guillam wonders how Haydon could have learned of the emergency, to which Smiley informs him that Haydon was having an affair with Ann. Smiley interviews Prideaux, now working at a rural prep school. Prideaux explains that his Budapest mission was to identify the mole and relay one of five code-names to Control drawn from the English children's rhyme " Tinker, Tailor ". Alleline was "Tinker", Haydon "Tailor", Bland "Soldier", Esterhase "Poorman", and Smiley "Beggarman". However, he was captured and tortured by the KGB, during which he witnessed Irina's execution. During his interrogation, Karla personally visited and asked how close Control was to identifying the mole before trading Prideaux back to the Circus. Smiley realises that Witchcraft is actually a KGB ruse. Alleline and his allies believe that Polyakov is giving them invaluable intel from a "high-placed source": Karla. In fact, the intel is largely fake or exaggerated, with just enough to make it appear genuine. Smiley informs Lacon and the Minister that the true object of Witchcraft is to form a partnership between the Circus and the CIA, enabling the mole to leak both British and American intel. To draw out the mole, Smiley instructs Tarr to hold the Paris Station at gunpoint and force them to send a fake cable to the Circus. To ensure his compliance, Smiley agrees to Tarr's request to trade the mole for Irina, despite knowing she is dead. Smiley and Guillam surprise Esterhase as he leaves the Circus and drive him to an airstrip and waiting plane; Esterhase gives them the address to the safe house rather than be deported. Smiley and Guillam wait at the safe house for the mole to alert Polyakov that Tarr is about to blow their cover. The mole is revealed to be Haydon, and Smiley arrests him at gunpoint. The Circus holds Haydon at its training and debriefing facility, Sarratt. Smiley informs him he will be traded for British operatives held in the Soviet Union, and agrees to settle several of Haydon's sexual relationships with both women and men. Haydon informs him that Karla ordered him to seduce Ann to cloud Smiley's judgment. He also confirms that Prideaux, a long-time friend (and, it is hinted, lover), suspected Haydon was the mole and tipped him off before his Hungary mission. Haydon was able to inform Karla and prevent Prideaux from being killed by the KGB. Blaming Haydon for allowing his torture, Prideaux infiltrates Sarratt with a hunting rifle and kills Haydon from a distance, shooting him in the cheek and watching as he collapses. Ann returns home, Alleline is dismissed from the Circus in disgrace and retires, and Smiley is reinstated and takes up his new post as chief.