FBI Special Agent Anthony Hubbard and his Lebanese-American partner Frank Haddad intervene at the hijacking of a bus fully loaded with passengers, which contains an explosive device. The bomb turns out to be a paint bomb and the terrorists escape. The FBI receives demands to release Sheikh Ahmed Bin Talal, a suspect in an earlier bombing. Hubbard is confronted by Central Intelligence Agency operative Elise Kraft while taking a different suspect into custody and arrests her. Later, another terrorist threat is made and a Metropolitan Transportation Authority bus is suicide bombed, killing 25 people. The FBI captures Samir Nazhde, a man who admits to signing the visa application of one of the suicide bombers in the course of signing many applications for student visas in his job as a lecturer. Kraft insists that Samir, with whom she has a sexual relationship, is not a terrorist and that his continued freedom is vital to the investigation. Hubbard and his team track down and eliminate the terrorist cell and believe that the threat is over. However, the terrorist incidents escalate with the bombing of a crowded theater and a hostage situation at an elementary school, and culminate in the destruction of One Federal Plaza, the location of the FBI's New York City field office, causing more than 600 deaths. Over the objections of some of his advisors, the President of the United States declares martial law and the Army 's 101st Airborne Division, under Major General William Devereaux, occupies and seals off Brooklyn to locate the remaining terrorist cells. All young men of Arab descent, including Haddad's son Frank Jr., are rounded up and detained in Downing Stadium. Haddad resigns in outrage while New Yorkers stage violent demonstrations against the Army’s occupation and the profiling of Arabs. Hubbard and Kraft, now revealed to be intelligence operative Sharon Bridger, continue their investigation and capture a suspect, Tariq Husseini. Devereaux, who was surveilling Hubbard, tortures and kills Husseini in the course of the interrogation. Husseini reveals nothing of value because of the principle of compartmentalized information. Sickened, Bridger concedes that she provided training and support to militants opposed to Saddam Hussein ' s regime, working with Samir to recruit and train the followers of the Sheikh. After the cut of their funding and the group was left to be exposed, she took pity on the few of the victims who had not yet been slaughtered by Hussein's forces, and arranged for them to escape to the United States, ultimately leading to the present situation as they direct their bomb making and covert skills on the country that now holds their leader. The Sheikh was also apprehended by Devereaux without any consent from the U.S. government. She and Hubbard compel Samir to arrange a meeting with the final terrorist cell. Hubbard convinces Haddad to return to the FBI. A multi-ethnic peace march demonstrates against the occupation of Brooklyn. As the march begins, Hubbard and Haddad arrive at the meeting place, but Bridger and Samir have already departed. Samir reveals to Bridger that he is in fact the final bomber while also predicting that, "there will never be a last cell," as their terrorist acts are just a beginning. He straps a bomb to his body, intending to detonate it among the marchers. Hubbard and Haddad arrive in time to prevent him from leaving a bathhouse, but Samir shoots Bridger in the stomach as she struggles to stop him. Hubbard and Haddad kill Samir but can only watch as Bridger succumbs to her wound after reciting lines of the second half of the Lord's Prayer and concluding with " Inshallah ". Hubbard, Haddad, and their team raid Devereaux's headquarters to arrest him for the torture and murder of Husseini and the unauthorized detaining of the Sheikh. Devereaux insists that under the War Powers Resolution the authority vested in himself by the President supersedes that of the court which issued the arrest warrant. He then commands his soldiers to aim their assault rifles at the agents, resulting in a Mexican standoff. Hubbard reminds Devereaux that the civil liberties and human rights which he took from Husseini are what all of his predecessors have fought and died for. Devereaux finally submits and is arrested. Martial law ends and the detainees, including Haddad's son, are given their freedom.

Major Thomas Egan is an officer with the U.S. Air Force stationed at an Air Force Base near Las Vegas, Nevada. He is a former F-16 Falcon pilot, married, with two children who live with him in a suburban house off-base. His current assignment involves flying armed MQ-9 Reaper drones in foreign air space in support of the U.S. war on terror. He is admired by his commanding officer and support staff for his calm demeanor, precise flying, and adaptability. Privately, he is concerned about the assignment, which he took after being informed there was reduced call for and increased competition among fighter pilots in the Air Force. His previous CO informed him that a tour flying unmanned aerial vehicles (UAVs) would look good on his record and would increase his chances of being posted back to a flying assignment. At first, the new assignment seems stressful but relatively benign. He is assigned to attack more clear-cut terrorist cells, vehicles, and facilities in Afghanistan. He flies these assignments during daylight hours over his targets, which is night-time in Las Vegas, leaving his days free for his sleep period, and to spend time with his wife and children. However, the high-tempo assignment – he is attacking targets on almost a daily basis – begins taking its toll. His wife notices the stress he's under and he begins drinking when off-duty. Still, his performance is excellent and his crew is rated among the highest in the squadron, so, on the orders of his commanding officer, he is assigned to more challenging missions under the direction of CIA controllers. Many of these targets are in Yemen and Somalia, places where the U.S. has no acknowledged military mission. The targets themselves are increasingly morally ambiguous: crowds the CIA controller calls terrorist cells, public buildings the controller says are sleeping spots for high level terrorist leaders or factories for making explosives. Collateral damage goes from being a rare occurrence to a routine one. On several occasions, the CIA controller orders strikes on obvious civilian targets – including women and children – describing these casualties as unfortunate but necessitated by terrorist leaders using them as human shields. Egan's performance declines and his drinking intensifies. He narrowly avoids being arrested for drunk driving, and starts avoiding home commitments, not wanting to inflict the stress he's under on his wife. He relishes a rare overwatch assignment protecting U.S. troops as they sleep, but must break a promise to his wife in order to perform the mission. On another overwatch mission, the troops are killed by an improvised explosive device that Egan could not protect them from. After a stress-induced violent episode at home, Egan's wife demands to know the details of Egan's work, and Egan tells her. She appears appalled. Soon after, she says she is leaving him and taking the children to Reno, Nevada, blaming his drinking and violent behavior. Finally, Egan cracks. His CIA controller orders a strike on a small group of civilians responding to an explosion at a building Egan had previously destroyed. Rather than obey the order, Egan simulates a glitch in the UAV control system and the targets escape. His CO has no choice but to demote him away from the attack role into a surveillance one. While on a surveillance mission, Egan notices a man whom he had previously watched rape a woman several times approaching her home. His Mission Intelligence Coordinator had previously described this man as "a bad guy. But not our bad guy." Egan conspires to send his support staff on a break, then uses the surveillance UAV to attack and kill the rapist. He then leaves the base without orders and is seen driving away from Las Vegas toward Reno.

Volunteers arrive for a psychological study led by Dr. Archaleta (Stevens), among them Travis (Brody), a proud anti-war protester, and Michael Barris (Whitaker), a 42-year-old man who still lives with his domineering mother. After interviews measuring responses to scenes of violence, a chosen 26 are driven to an isolated prison setting with 24 hour camera coverage. The group is split into six guards and 20 prisoners, thereafter referred to only by number. Travis is assigned as a prisoner (#77), and Barris as a guard. Prisoners are required to fully consume three meals a day, participate in 30 minutes of daily recreation, remain within designated areas, and avoid speaking to guards unless spoken to first. Guards must ensure prisoners obey the rules and deal commensurately with transgressions within 30 minutes. Archaleta stresses that the experiment will end immediately at the first sign of violence or quitting. If all rules are followed for two weeks, each man will be compensated $14,000. Travis' cellmates are Benjy, a graphic novelist, and Nix, a member of the Aryan Brotherhood who served prison time before. Barris, concerned that some guards may be capable of violence, tries to dissuade them from aggressive behavior. Instead, the guards grow more forceful to make prisoners 'obey at all costs'. Barris gradually becomes more sadistic. Realizing that the defiant Travis is influencing prisoner dissent, Barris instructs other guards to abduct him, shave his head, and urinate upon him. When Archaleta fails to intervene, Barris reasons that his actions were "commensurate". When fellow guard Bosch dissents, Barris pressures him to continue. Travis discovers that Benjy, now severely ill, concealed his need for insulin, believing he could cure his diabetes merely through dieting. Bosche tries to help find Benjy's insulin, but is caught by other guards. Barris provides Benjy's insulin, but later has all the guards beat Bosche severely and orders Travis to clean the prison toilets. When Travis taunts Barris, the guards respond by shoving his head into the toilet, nearly drowning him. One morning during roll call, Travis removes his shirt as a sign of protest, followed by the other prisoners. He climbs up to one of the cameras and demands they be released, but the guards choke him. When Benjy tries to defend Travis, Barris bludgeons him. Guards lock Travis into an old boiler pipe overnight, attack the remaining prisoners, and handcuff each man across the cell doors. While locked in the boiler, Travis discovers a hidden infrared camera. As his despondency turns to anger, he manages to escape and interrupts a guard’s attempt to rape a prisoner. The intended victim and Travis beat the guard and knock him out before freeing the other prisoners. Finding Benjy dead from his head injury, Travis leads an assault against the guards, chasing them through the building. As the remaining guards try to lift the garage door to escape, Barris tries to keep them in, unwilling to forfeit his power. A vicious brawl ensues with the prisoners overwhelming the guards. Travis personally confronts Barris, who tries to stab him, only for Travis to stop the blade with his bare hand. Shocked by his own actions, Barris allows Travis to beat him to a pulp. Only then does the door open, signaling the end of the experiment. The group emerges into bright sunlight and sits on the grass in silence until a bus arrives. Audio news snippets suggest that Archaleta is being tried for manslaughter in Benjy's death. Travis, having received his payment, travels to India to meet his girlfriend.

A man calling himself Ryder and his accomplices – Bashkin, Emri, and former train operator Phil Ramos – hijack Pelham 123, a New York City Subway 6 train, at 77th Street. Uncoupling the front car of the train below 51st Street, they take its passengers hostage. Metropolitan Transportation Authority employee Walter Garber, working the Rail Control Center as a train dispatcher, receives a call from Ryder, demanding $10 million in cash to be paid within 60 minutes. Ryder warns that every minute he waits past the deadline, he will kill a hostage. He kills an intervening plainclothes New York City Transit Police officer. Garber reluctantly negotiates with Ryder as Ramos and Emri set up Internet access in the tunnel. On his laptop, Ryder watches the Dow Jones Industrial Average plunge nearly 1,000 points in response to the hijacking. A hostage's laptop also connects to the Internet, and its webcam allows the control center to observe Ryder and Ramos. Lieutenant Camonetti of the New York City Police Department Emergency Service Unit takes over negotiations, which infuriates Ryder, who kills the train's motorman to force Camonetti to bring Garber back. Camonetti learns that Garber is being investigated for allegedly accepting a $35,000 bribe over a contract for new subway cars. Ryder also discovers the allegations online and forces Garber to confess by threatening to kill a passenger. To save the hostage, Garber claims that he was offered the bribe while deciding between two companies, using the money to pay for his child's college tuition, and insists he would have made the same decision regardless. The mayor agrees to Ryder's ransom, ordering the police to bring it. En route, the police car crashes, failing to deliver the money in time. Garber attempts to bluff Ryder that the ransom has arrived, unaware he has been monitoring events on his laptop. Ryder threatens to execute a child's mother, but another hostage, a former soldier named Wallace, sacrifices himself and is killed. A brief gunfight erupts after an Emergency Service Unit sniper is bitten by a rat and discharges his weapon, killing Ramos. Based on clues from Garber's conversations, the police discover that Ryder is Dennis Ford, a manager at a private equity firm who was sentenced to prison for investment fraud. Ford had agreed to a plea bargain to serve three years, but received ten years instead. One of the mayor's aides mentions the extreme drop in the major stock indexes, and the mayor infers that Ryder is attempting to manipulate the market via put options. Ryder demands that Garber deliver the ransom money himself to avoid coming in contact with the police. Garber is flown to the terminal, where he is given a pistol for protection. Ryder brings Garber aboard and orders him to operate the train down the tunnel below 33rd Street, where Garber and the hijackers exit, rigging the train to go on without them. Garber manages to separate himself at a railway crossing and then follows Ryder to Track 61 underneath Waldorf Astoria hotel. Ryder parts from Bashkin and Emri, who are shot dead after being surrounded by police and provoking deadly force in an apparent suicide by cop. The train comes to a screeching halt safely just before Coney Island (West 8th Street-New York Aquarium), and the police discover that Ryder is no longer on board. Ryder hails a taxi, with Garber following him on-foot, and finds out that his scheme has amassed $307 million. Garber steals a car and pursues Ryder. After a brief chase, they reach the Manhattan Bridge 's pedestrian walkway, where Garber catches up with Ryder and holds him at gunpoint. Ryder gives him a 10-second ultimatum to pull the trigger, and in the final seconds, pulls out his own gun, forcing Garber to shoot him. Telling Garber in his final breath, "You're my goddamn hero", as Garber solemnly looks on and Camonetti observes approvingly from a helicopter. The mayor thanks Garber and assures him the city will "go to bat" for him over his bribery admission. The film concludes as Garber returns home to his wife with groceries he had promised to pick up.

Carter Hayes and Ann Miller are suddenly attacked and beaten by two men. After the men have gone, Hayes calmly tells Ann, "The worst part's over now...." In San Francisco, couple Drake Goodman and Patty Palmer purchase a 19th-century Victorian house in the exclusive Pacific Heights neighborhood. They rent one of the building's two first-floor apartments to the Watanabes, a kindly Japanese couple. Soon after, Hayes visits to view the remaining vacant unit, driving an expensive 1987 Porsche 911 and carrying large amounts of cash, but is reluctant to undergo a credit check. He convinces Drake to waive the credit check in exchange for a list of references and an upfront payment of the first six months' rent, to be paid by wire transfer. Before any of this money is paid, however, Hayes arrives unannounced and shuts himself in the apartment. As the days pass, Hayes' promised wire transfer fails to materialize. From inside the apartment, sounds of loud hammering and drilling are heard at all hours of the day and night; however, the door is seldom answered. When Drake finally attempts to enter Hayes' apartment, he finds that the locks have been changed. Drake cuts the electricity and heat to the apartment, but Hayes summons the police, who side with Hayes and reprimand Drake. Drake and Patty hire a lawyer, Stephanie MacDonald; however, the eviction case is thwarted by Drake's actions. Hayes, safe from eviction for the time being, infests the house with cockroaches, which prompts the Watanabes to move out and pushes Drake and Patty further into debt. The stress takes its toll on the couple; Drake drinks heavily and Patty suffers a miscarriage. Hayes visits the couple, supposedly to offer his condolences, but an infuriated Drake attacks him and is arrested by the police, whom Hayes had already called to the scene in anticipation of an assault. The assault allows Hayes to file a civil lawsuit against Drake and, unbeknownst to the couple, assume control of Drake's possessions and identity. Hayes also files a restraining order, which forces Drake from the building. Once Drake is gone, Hayes begins stalking and harassing Patty. When Drake tries to enter the home to check on Patty, Hayes confronts Drake and shoots him, then plants a crowbar at the scene to prevent any criminal charges. While Drake is in the hospital, the eviction is finally handed down and authorities force entry into Hayes' apartment. By this time, however, Hayes has disappeared, and the apartment has been destroyed and stripped bare. Later, while cleaning out the destroyed apartment, Patty finds an old photograph of Hayes as a young boy. Written on the back is the name "James Danforth". She phones Bennett Fidlow, the Texas attorney whom Danforth had provided as a reference. Fidlow tells her that Danforth has a long history of wrongdoing and has been disowned by his family. Patty travels to Danforth's last-known address, a condominium in Desert Spring. There she finds Ann, his girlfriend and previous co-conspirator who had earlier come looking for him in San Francisco. Ann tells Patty that Carter Hayes is the name of the property's former landlord, and that Danforth assumed Hayes' identity and took possession of the condominium after (the genuine) Hayes hired two thugs to carry out the assault on Hayes and Miller. Ann also shows Patty a postcard from Danforth, written on the letterhead of a hotel in Century City, which had just arrived the day before. Patty tracks Danforth at the hotel, where he has checked in under Drake's name. Patty bluffs her way into his suite by posing as his wife, and while rummaging through his personal effects discovers he is using legal and financial documents in Drake's name. She calls Drake and tells him to cancel all of his credit cards and freeze the couple's joint bank account. She then places an exorbitant order for room service, which leads to Danforth being arrested. Danforth is bailed out of prison by a wealthy widow, Florence Peters, whom he was vetting to be his next victim. Once out on bail, Danforth returns to San Francisco to seek revenge on Patty and Drake, unwilling to accept responsibility for his actions and blaming them for his desires being ruined forever. Upstairs, he bludgeons Drake with a golf club, then attacks Patty in the downstairs apartment where she is busy making repairs. A struggle ensues, and a badly wounded Drake makes his way into the crawl space between the basement and the first-floor apartment. He reaches through a hole in the floor and grabs Danforth by the ankle while Patty pushes him away, causing Danforth to lose his balance and fall backward, landing on a water supply line and getting impaled in the process; a wounded Danforth desperately tries to escape, but is unable to and ultimately dies of his injury. Some time later, Patty and Drake have put their newly repaired building up for sale and show the property to another couple. The story ends with the couple having a private discussion about making an offer of $825,000-$850,000, which is $75,000-$100,000 more than what Drake and Patty had originally paid for it.

Lucy is an American studying in Taipei. Her new boyfriend Richard coerces her into delivering a briefcase containing four bags of the highly valuable synthetic drug CPH4 to Mr. Jang, a South Korean drug lord, at the Regent Taipei. After witnessing Richard being shot dead, she is captured and forced to become a drug mule. One bag of the drug is sewn into her abdomen for transport to Europe. She is kicked in the belly, breaking the bag and releasing a large quantity of the drug into her system. She acquires enhanced physical and mental capabilities, such as telepathy, telekinesis, mental time travel, and negated emotions; she also ceases to feel pain. Using her new abilities, she kills her captors and escapes. Lucy travels to the nearby Tri-Service General Hospital to get the bag of drugs removed. She is told by the operating doctor that natural CPH4 is produced in tiny quantities by pregnant women during their sixth week of pregnancy to provide fetuses with the energy to develop. As her abilities continue to develop, Lucy returns to Mr. Jang's hotel, kills his bodyguards, assaults him, and telepathically extracts the locations of the drug mules who are carrying the three other bags of CPH4. Lucy contacts scientist Samuel Norman, whose research about the brain's capacity helps her understand her condition. Lucy demonstrates proof of her abilities to an amazed Norman and tells him she will die in 24 hours. When she asks what she should do with her newfound knowledge, Norman suggests she pass it on. Lucy agrees and flies to Paris to meet with him. She contacts local police captain Pierre Del Rio to help her find the other three drug mules. During the flight, she has a sip of champagne, which initiates a drug interaction that causes her cells to become unstable. To stave off this process, Lucy ingests more of the drug. With the help of Del Rio, Lucy is able to recover the rest of the drugs. Meeting Norman and his colleagues, she agrees to share with them everything she knows. In the professor's lab, Lucy discusses the nature of time and life and how people's humanity distorts their perceptions. At her urging, she is intravenously injected with the contents of all three remaining bags of CPH4. As Lucy's brain capacity begins to rapidly increase, her body changes into a black substance that begins spreading over computers and other electronic devices in the laboratory, combining with them and transforming into a single supercomputer. She mentally begins a journey through spacetime into the past, eventually reaching the oldest discovered ancestor of mankind, Lucy. She shares a quiet moment with Lucy and the two touch fingertips, before she goes all the way to the beginning of time and witnesses the Big Bang. Meanwhile, Jang enters the laboratory and points a gun at Lucy, whose body has reformed. He shoots at her head, but by that point Lucy has reached 100% of her brain capacity and promptly vanishes, moving into the space-time continuum. Only her clothes and the black supercomputer are left behind. Del Rio enters and fatally shoots Jang. Norman takes a black flash drive offered by the supercomputer, after which it, too, disintegrates. Del Rio asks Norman where Lucy is, immediately after which Del Rio's cell phone sounds and he sees a text message: "I am everywhere." Lucy's voice is heard stating "Life was given to us a billion years ago. Now you know what to do with it."

Scientists invent a brain–computer interface that records sensations from a person's brain on tape for others to experience. The team includes estranged husband and wife Michael and Karen, as well as Michael's colleague Lillian. At CEO Alex's instruction, the team demonstrates the device to investors to gain financing. Karen dons the recorder while working with Michael and Lillian. When Michael plays the tape back, the group realizes that emotional experiences are also recorded. Michael tapes his memories of times with Karen, which he shares with her, leading to their reconciliation. Alex and his investors pressure Lillian to accept Landan, who works for the federal government and has ties to the military, on the team. Karen vehemently opposes their plan to have the invention developed for military use. One team member, Gordy, has sexual intercourse while wearing the recorder, and shares the tape with colleagues, including Hal. Hal splices one section of the tape into a continuous orgasm, which results in sensory overload, leading to his forced retirement. Tensions increase as the possibilities for abuse—and not only by the military–industrial complex —become clear. A chain smoker, Lillian suffers from heart problems. She has a heart attack while working alone. Realizing she is about to die, Lillian records her experience. Michael decides to play Lillian's recording, but nearly dies when his body relives her heart attack. Michael modifies his console to filter the physical output and replays the tape. He sees "memory bubbles"—moments from Lillian's life. Michael experiences Lillian's memories of a humorous exchange with Michael as he plays with an industrial robot, a surprise birthday party, and being devastated when Alex tells her that an earlier project is canceled. Landan's men monitor the equipment while Michael plays Lillian's tape. They have Gordy plug in, but Landan ignores the staff's warning that Michael modified his terminal. Gordy dies from experiencing Lillian's heart attack. Michael's playback is cut short by Hal, but witnessing the near-death experience makes Michael eager to see the entire tape. Alex has the recording locked away and tells Michael he will not be allowed to view it. When he returns to work, Michael walks in on Landan and outside technicians going through his research records. Alex responds to his protests by firing Michael and Karen. Michael attempts to hack into the lab's computers. Hal advises him to look under "Project Brainstorm", a program the military created to use their invention for torture and brainwashing. Michael accesses a tape from his den and quickly stops viewing it because of its disturbing nature. Michael and Karen's son Chris inadvertently views the tape, causing a psychotic break that requires hospitalization. Alex visits and Michael confronts him about Project Brainstorm, blaming Alex for his son's condition. Alex denies any knowledge of the project, then informs Michael of Gordy's death. Michael vows to destroy his work and enlists the help of Karen and Hal. Michael and Karen head to the Pinehurst Resort, and realizing they are under surveillance, stage a fight that ends in Karen leaving for Hal's house. As the two feign reconciliation over the phone, Michael accesses the Brainstorm computer via another phone line while Karen hacks into the system, sabotaging the robots that manufacture the interface terminals. They run amok. Karen shuts down the security system, locking the staff outside. Michael loads Lillian's tape. With the plant in chaos, Brainstorm manager Robert orders Michael's arrest. Karen leaves to meet with Michael at a place important to them. Hal and his wife, Wendy, send the last of Karen's commands to the company computers, shutting down the plant. Karen follows Michael to a phone booth at the Wright Brothers memorial. The tape plays. Michael bears witness to the afterlife, experiencing a vision of hell, then traveling from Earth and through the universe, even after the tape ends. He ultimately has visions of angels and departed souls flying into a great cosmic Light. Then he collapses. Karen, believing him dead or dying, screams at him, over and over, demanding that he stay with her. Awakening, weeping with joy, Michael points up and whispers, “Look at the stars!” Their embrace, enclosed in a memory bubble that floats into the night.

On Walter Sparrow's birthday (February 3), his wife Agatha gives him The Number 23, a book by Topsy Kretts, as a birthday present. Walter starts reading it and notices similarities between himself and the main character, the detective " Fingerling ". Fingerling is obsessed with the 23 enigma, the idea that all incidents and events are connected to the number 23. Walter too becomes obsessed with the number and attempts to uncover the mystery of the book's author, but he cannot find any information. Walter's son, Robin, is interested in the enigma too, but Agatha dismisses it as superstition. In the book, Fingerling discovers that his lover, Fabrizia, is having an affair and stabs her to death. The police arrest her lover because he found her body and picked up the murder weapon, assuming it was a type of sexual roleplay. Fingerling then prepares to commit suicide by jumping from a hotel balcony, and the book ends abruptly. Walter later learns of Laura Tollins, a murder victim whose body was never found, and whose murder is similar to Fabrizia's death. Walter believes that the man who was sent to prison for Laura's murder, Kyle Flinch, wrote the book. In prison, Walter visits Flinch, who denies killing Laura or writing the book. Robin discovers an address hidden in the book and they hope that it will lead them to the book's true author. When Walter confronts the man, Dr. Sirius Leary, he commits suicide by cutting his own throat. Before dying, Leary tells Agatha to go to a now-abandoned mental institution that he used to work at. At the institute, Agatha discovers a box with Walter's name on it. Walter discovers a code in the book that tells the reader the location of Laura's body. Walter and Robin find the skeleton, but when they return with the police, the skeleton is missing. After seeing Agatha washing mud off her hands, she admits that she moved the skeleton. Walter accuses her of being Topsy Kretts. However, Agatha says that Walter was really the one who wrote the book. Agatha shows Walter the box from the institute that has his name on it. Inside, Walter sees the sources he used to write the book, and begins having flashes of repressed memories. In room 23 of the hotel in the book, Walter finds the missing final chapter of the book scribbled under the wallpaper. Walter used to be obsessed with the 23 enigma because it drove his father to suicide. He was also involved with Laura, who left him for Flinch, resulting in him killing her. After Flinch was sent to prison for the murder, Walter wrote the book in the room as an elaborate suicide note, changing the details of his confession into a deranged fantasy. Walter then jumped off the balcony, but survived. The resulting brain damage left him with amnesia, and he was sent to the institute to recover, and met Agatha after being released. Dr. Leary, one of Walter's doctors, read the book and became obsessed with the number, eventually publishing the book under the name Topsy Kretts. Agatha arrives, and tells Walter that he has changed, which is why she hid the skeleton. Convinced that he will kill again, Walter attempts to commit suicide by running into the path of a bus. However, Walter does not go through with it, not wanting Robin to lose a father like he did, and exclaims that 23 is just a number. Walter turns himself in to the police for the murder of Laura. While he awaits sentencing, his lawyer says that the judge will go easy on him because he confessed. Walter declares that this is not the happiest ending, but it is the right one, and expresses hope that things will return to normal for his family once he is released from prison. Laura's body is laid to rest in the cemetery, and Flinch is present, having been released from prison and now at peace. The credits begin with a Bible verse (Numbers 32:23), which reads: "Be sure that your sin will find you out."

Best friends Becky Connor and Shiloh Hunter are climbing a mountain with Becky's husband Dan, who is startled by a bat and falls to his death. A year later, Becky has given up climbing and become a recluse contemplating suicide. She has estranged herself from her father James, because he thinks Dan would not have grieved as she has if the situation were reversed. Just before the anniversary of Dan's death, Shiloh invites Becky to climb the decommissioned 2,000-foot (610 m) B-67 TV Tower in the desert before it is demolished. Shiloh suggests she scatter Dan's ashes from the top as a form of healing. A reluctant Becky accepts, hoping to finally move on from Dan's death. The next day, Shiloh and Becky arrive and climb several severely corroded ladders to a tiny platform at the top of the tower, where Shiloh goads Becky into momentarily free-hanging off the platform, while Shiloh records for her YouTube channel. Becky scatters Dan's ashes. As the two begin their descent, the ladder breaks. Becky falls but is caught by a rope connecting her to Shiloh. Shiloh pulls Becky back up and they realize they are now stranded hundreds of feet above the next intact ladder. Becky's thigh has also been cut. Their backpack with their water and a small quadcopter drone falls onto a communications dish below them. Despite the remote location, Shiloh is confident that someone heard the crash of the ladder, but help does not arrive. They try to use their cellphones, but radio interference from the communications dish blocks the signal. Shiloh sends a message for help to her Instagram followers by packing her phone in a shoe and dropping it outside the range of the interference. The pair notice a man and his dog but cannot get his attention. The man joins another man camping in an RV nearby. They wait till night and use a flare gun found in an emergency box on the platform to alert the men. The men see the flare, but they steal Shiloh's car and drive off. The pair realize Shiloh's phone dropped in the shoe must have been smashed as still no help has come. Becky notices a tattoo on Shiloh's ankle: "1-4-3", a code Dan used to say "I love you" to Becky. Shiloh tearfully admits to a four-month affair that ended before Becky and Dan's wedding. The next day, Shiloh climbs down using the rope to retrieve the backpack with water but nearly falls. Shiloh injures her hands but successfully ties the rope to the bag, and Becky uses all her strength to pull both Shiloh and the backpack up. Becky has a nightmare of a vulture eating Shiloh's dead body. Becky uses power from the tower's aviation obstruction lighting warning light to charge the drone, whilst being attacked by a vulture, and sends the drone to a nearby motel with a written message for help, but the drone is struck by a truck and destroyed. Becky is delirious from dehydration, but in a brief lucid moment, she realizes Shiloh fell onto one of the communication dishes when retrieving the backpack and died; Becky has been hallucinating her presence since then. The next day, Becky is awakened by a vulture gnawing at her wounded leg; she kills the vulture and eats it. Her strength partially restored, she abseils down to the dish where Shiloh's body lies. Becky types a text message to her father on a second phone, then puts it in Shiloh's shoe and shoves them into Shiloh's body before pushing the body off the tower. Shiloh's body cushions the impact and the message transmits. James alerts emergency services, who then rush to the tower. Becky and James reunite and reconcile.

Structural engineer John Garrity lives in Atlanta, Georgia, with his estranged wife, Allison, and their diabetic son, Nathan. He is on the way home to watch the near-earth passing of a recently discovered interstellar comet nicknamed "Clarke", along with his family and neighbors. While at the supermarket, John receives an automated DHS message announcing that he and his family have been selected for emergency sheltering. He returns home just as a comet fragment is seen entering the atmosphere on live TV. Previously expected to land in the ocean near Bermuda, the fragment instead strikes Tampa, vaporizing the city along with most of the state. John then receives a call with instructions to head to Robins Air Force Base for an evacuation flight, as Clarke is on a direct collision course to Earth and the impact will cause an extinction-level event in two days. John, Allison, and Nathan pack up and drive away. The way to the base is clogged by heavy traffic, so the Garritys abandon their car and continue on foot. Nathan's insulin is accidentally left behind in the car. As they reach the base, John realizes it is missing and goes back to retrieve it. Meanwhile, Nathan's medical condition is discovered, disqualifying him for sheltering, and Allison stays with him. John returns and boards a plane, but quickly jumps off upon realizing Allison and Nathan were left behind. As John exits the base, a panicked mob breaks in, destroying several evacuation planes when gunfire ignites spilled jet fuel. Returning to their car, John finds Allison's note saying they are going to her father's home in Lexington. After getting medical supplies, Allison and Nathan hitch a ride with Ralph and Judy Vento, only for Ralph to kidnap Nathan to use him and the wristbands to board a flight. John hitch-hikes a ride on a military truck full of people heading towards Canada, planning to get off in Lexington. A passenger named Colin tells him they are headed to Osgoode, Ontario, where private planes are flying to Greenland, believed to be the military evacuation site. Another man attempts to steal John's wristband, causing the truck to crash, killing Colin. John is forced to kill the other man in self-defense. At another air force base, the Ventos attempt to pose as Nathan's parents, but are arrested when Nathan reveals he's not their child. Allison and Nathan are reunited shortly after at a nearby FEMA camp in Knoxville. The following morning, John learns that the largest fragment will hit in approximately 24 hours. Stealing a car, John reaches his father-in-law, Dale's, house, and Nathan and Allison arrive shortly after. The family learn about a complex of underground bunkers near Thule Air Base in Greenland, confirming that is where the evacuees are being sent. Dale chooses to stay behind, bidding farewell to his daughter's family. John, Allison, and Nathan proceed in Dale's truck. While making steady progress to Osgoode, the family learns over the radio that Clarke's largest fragment, which is 9 miles (14 km) wide, will hit Western Europe and obliterate it. They arrive at the Osgoode airport just in time to board the last flight out. As they reach Greenland, a comet fragment strikes, causing the plane to crash and hit a glacier,killing the pilot. The Garritys and the rest of the passengers flag down a military truck and enter the bunker complex just as the largest fragment enters the atmosphere and hits Earth, devastating civilization along with the world. Nine months later, the bunker makes radio contact with other survivors around the world. The Garritys and other occupants exit the shelter, as reports come in that the atmosphere is finally clearing, giving the survivors the chance to bring Earth back onto its feet.

In the year 2078, the planet Sirius 6B, once a thriving mining hub, has been reduced to a toxic wasteland by a war between the mining company the New Economic Block (N.E.B.) and "The Alliance", a group of former mining and science personnel. A fragile stalemate is in effect between the two exhausted, poorly-supplied, and undermanned armies. The vast empty areas between the two sides are patrolled by Autonomous Mobile Swords (AMS)— AI -powered robots developed by Alliance scientists. Nicknamed "Screamers" after their signature high-pitched noise, they target creatures with a heartbeat. Alliance soldiers wear "tabs" that disguise their heartbeats, rendering them invisible to the machines. An N.E.B. soldier carrying a message to the Alliance compound is killed by screamers. The message guarantees safe passage through N.E.B. territory to discuss a truce. Alliance commanding officer Joe Hendricksson reports this development to his Earth-based superiors, but is told to disregard it as peace negotiations are already underway on Earth. Private "Ace" Jefferson, the only survivor of a crash of a transport newly arrived from Earth, rebuts this claim. Hendricksson is not surprised; he has long suspected that both sides have simply written off Sirius 6B and abandoned their armies. Deciding the truce is their only chance of survival, Hendricksson, accompanied by Jefferson, sets out to meet the N.E.B. commander. While traveling through a ruined city they come upon David, a young boy clutching a teddy bear. Unwilling to abandon a defenseless civilian, they bring him along. The following night, they are attacked by a new "Type 1" screamer model immune to the tabs, alarming Hendricksson. As the group nears the N.E.B. compound, two enemy soldiers, Becker and Ross, open fire on David, who explodes in a shower of bolts and gears. Alliance men are shocked to learn he was a "Type 3" screamer. Most of the N.E.B. contingent has been wiped out by another "David" screamer that a patrol unwittingly brought into the base. Becker, Ross, and a black marketeer named Jessica are the only survivors. The group heads to the N.E.B. command center but finds it abandoned. Locating the mainframe computer, Hendricksson learns that the N.E.B. truce offer was just as false as the Alliance message from Earth. Hendricksson sees a "type 1" downloading information from the mainframe. He attempts to query the mainframe for "type 2" but approaching "Davids" force them to retreat. Back at the N.E.B. bunker, the knowledge of Screamers creating new versions that are indistinguishable from humans make everyone paranoid. Becker becomes convinced that Ross is a screamer and kills him, only to discover that he was human. The four survivors retreat to the Alliance base, only to find that it has been taken over by "Davids". As dozens of "Davids" pour out of the bunker's entrance, Hendricksson wipes them out with a micro-nuclear missile. Jefferson rushes to help Becker, who was apparently injured in the blast. However, Becker revealed himself to be a "type 2" and kills Jefferson. After Hendricksson destroys Becker, only he and Jessica remain. Worrying that Jessica could be a screamer, Hendricksson cuts her hand and is relieved to see blood. The pair locate an emergency escape shuttle, but discover it only seats one. Hendricksson offers the spot for Jessica but a second "Jessica" arrives, revealing she is another even more human-like model of screamer. Hendricksson resigns himself to death, but to his surprise, Jessica shields him, battles her lookalike, and is fatally wounded. The spacecraft's engines kick on and destroy the second "Jessica". With her last breath, the original Jessica confesses her love for Hendricksson, who departs for Earth with the teddy bear carried by the first "David". As the screen fades to black, the bear slowly begins moving.

Set in Saint Petersburg in 1860, the story revolves around retired officer Yakovlev. A deadly shot, Yakovlev is effectively a kind of mercenary in that he is available for hire through his associate Baron Staroe to stand in for others in formal duels. Much later in the film, flashbacks reveal that years ago an Aleut shaman has predicted he would never die, and so far that seems about right as Yakovlev wins duel after duel, wounding and more often killing noble opponents. Although duels of honor are technically illegal in Russia at the time, most people turn a blind eye to the law. The code of practice is not written down anywhere, and yet everyone knows the rules and rituals, while many participants see it as an almost mystical rite. To take part in a duel is to accept that one's fate is ultimately in the hands of God, hence the practice of Russian roulette. Eventually, it turns out that all of Yakovlev's recent duels were secretly arranged by Count Beklemishev. He is a shadowy puppet master with a grudge and designs on Princess Martha Tuchkova whose brother (Prince Tuchkov) Yakovlev is scheduled to duel with next. When attraction stirs between him and the pretty blond princess, problems arise, especially since, as the flashbacks reveal, Yakovlev has an agenda of his own.