Alice Ackerman works as a camgirl on a website called FreeGirlsLive under the name "Lola_Lola". Obsessed with her rank on the site, she hopes to become number one. Alice's mother believes she works in web development; her younger brother Jordan persuades Alice to tell their mother the truth. Alice has two loyal viewers, Barney and Arnold, with whom she regularly engages in direct messages. One night, while streaming, she commits suicide by slitting her throat at the request of an anonymous user (later revealed to be Arnold), only to then reawaken and reveal it was a stunt. While chatting with Barney that night, she learns that he will be in her area soon and agrees to a date with him. While shopping for Jordan's birthday, Alice sees Arnold. She angrily confronts him later, assuming he has moved to her area to be closer to her, though he insists that he simply coincidentally got a job nearby. One morning, Alice finds that she cannot access her FreeGirlsLive account, though the account is still active and streaming. She finds that the channel has been taken over by someone with her exact appearance and mannerisms. Alice contacts FreeGirlsLive's customer service, believing that they are replaying past shows, but they assure her that this is impossible. When Alice messages the channel, the "Lola" onscreen responds to her directly. Alice confides in her fellow camgirls, who agree that the situation is strange but deny responsibility for it. All of Alice's attempts to either access her FreeGirlsLive account or create a new one fail. At Jordan's birthday party, a fight ensues between him and his friends after they happen across one of the fake Lola's streams and ridicule her, inadvertently revealing the truth to her mother. Humiliated, Alice panics and leaves. That night, the fake Lola hosts a show in which she stages her own suicide by shooting herself in the mouth. Alice contacts the police, who are unhelpful and judgmental. When the fake Lola announces an upcoming joint show with fellow camgirl BabyGirl, Alice unsuccessfully attempts to get in contact with the latter. When "Lola" goes live during Alice's date with Barney, he assaults Alice, accusing her of lying about her identity to scam him, but she escapes. She later uses information provided by Barney to determine that Baby's real name is Hannah Darin and that the real Hannah died in a car accident six months prior. She searches for other camgirls she assumes to be doppelgängers, noticing that they each have Arnold as their top friend. Alice seeks Arnold out at his motel and begs for his help. He agrees, professing his love for her. She later falls asleep and awakens in the middle of the night to find Arnold in a private cam session with Lola. An enraged Alice demands answers; Arnold explains that he knows about the replicas, but is not behind them, nor does he know what causes them or how they work. Alice then talks to the fake Lola from Arnold's computer. The entity does not comment on the fact that they are identical, apparently unable to recognize what it is replicating. Alice angrily leaves, ignoring Arnold's pleas with her to stay. Alice goes home and sets up her vanity mirror, camera, and television in a position that creates an illusion showing multiple images of herself. She joins a private cam session with the fake Lola (who once again does not recognize her) and suggests that they go live together, to which the fake Lola enthusiastically agrees. Viewers chalk up the two Lolas to special effects. Alice challenges Lola to a game in which they imitate each other. Whoever the viewers think does the best wins—if Alice wins, she gets to ask anything of Lola. Alice is declared the winner after breaking her own nose. She demands Lola's password, then deletes the account just as it reaches the number-one rank. Some time later, Alice creates a new account, "EveBot", using a fake ID with the moniker "Emily Ramsay" and enlisting her mother's assistance with cosmetics. She cheerfully greets her viewers as her first stream as "Eve" begins.

James flees from a farmhouse and escapes into the woods. A screaming woman tries to follow, but is wounded by a gunshot. Lying on the ground, she is doused with gasoline and set on fire by Vincent and Simon. Deputy Sheriff Daniel Carter is on duty, sitting in his patrol car when he finds James crawling along the road and rushes him to the local hospital, which has been largely abandoned following a fire, where his estranged wife Allison Fraser works as a nurse. At the hospital are Dr. Richard Powell, nurse Beverly, intern Kim, pregnant patient Maggie, her grandfather Ben, and patient Cliff; with the staff at the hospital working as a skeleton crew. Daniel discovers an entranced Beverly murdering Cliff, her face flayed of skin. Beverly moves toward Daniel who shoots her dead. Daniel collapses due to a seizure and experiences a strange vision. State trooper Mitchell enters the hospital to collect James after discovering the bloody scene at the farmhouse. Daniel goes outside to call in Beverly's death from his patrol car but is tackled and stabbed by a robed cultist. He manages to return to the hospital as cultists surround the building. James, Daniel, and Mitchell find that Beverly's corpse has transformed into a tentacled creature. Vincent and Simon enter the lobby and hold the group at gunpoint, demanding to get to James. James takes Maggie hostage to protect himself and stabs Powell, who falls to the floor and dies. The Beverly-Creature appears and takes Mitchell, its tentacles penetrating his body. Vincent and Simon kill the Beverly-Creature and regroup with the others in the lobby, setting Mitchell's body on fire. Vincent and Simon accompany Daniel to retrieve a shotgun from a patrol car, while Allison ventures into the basement to collect medical supplies for delivering Maggie's baby. Powell, no longer dead, manages to capture Allison. Daniel and Vincent go to search for her and find photographs and files indicating Powell was the cult's leader. Powell phones Daniel from the in-house morgue, taunting him and mentioning the vision Daniel experienced while unconscious. Kim and Ben stay with Maggie while Daniel, Vincent, and Simon interrogate James. James explains that Powell has the power to transform people. The three men force James to come with them downstairs. Allison regains consciousness on an operating table where Powell explains he has found a way to defy death after the loss of his daughter Sarah. Having flayed off his face, Powell shows Allison that something now grows inside her belly. Daniel, Vincent, Simon, and James find a hidden area in the basement and end up surrounded by deformed corpses brought back to life. One of the creatures kills James as the other three men are separated. As Maggie enters labor, Kim hesitates to perform a C-section. As Ben pleads with Kim, Maggie stands and slits his throat, revealing she is carrying Dr. Powell's child. Kim hides as cultists enter the building and Maggie leaves to join Powell. Daniel finds Allison in the operating room pregnant. He sees a tentacled creature extending from her body. Powell's voice speaks to Daniel, who attacks his wife's mutated remains with an axe. Daniel is transported to a morgue room with a glowing triangle on the wall. Powell's voice tells Daniel that he found the ability to conquer life and death through a rite that enabled him to contact entities older than time itself. Powell promises that Daniel can have his child back if he is willing to die first. Maggie appears and stabs Daniel who is injured but alive. Powell appears skinless and partly mutated in front of the triangle as Maggie kneels before him. Powell recites an incantation before the triangle as a now frightened Maggie's torso explodes, giving birth to the Sarah-Creature. Vincent and Simon arrive and battle it. The Sarah-Creature overcomes Vincent, but he covers it in isopropyl alcohol, allowing Simon to set them both on fire with a flare. Powell tells Daniel he can be with Allison if he stops resisting and "let go". Daniel refuses and tackles him, leading both men to tumble into the void. Meanwhile, the Sarah-Creature pursues Simon, who escapes and is teleported back to the hospital to reunite safely with Kim. Daniel and Allison are shown holding hands in another world beneath a black pyramid while Powell's fate is left unknown.

In 1977, at Chicago 's Cabrini–Green housing projects, a young boy witnesses the killing of Sherman Fields, a homeless African American man with a hook for a hand. Suspected of giving a white child a razor blade in a piece of candy, Sherman is beaten to death by police but later proven innocent when more cases of razor blades in candies come up. In 2019, artist Anthony McCoy lives in Chicago with his girlfriend, gallery director Brianna Cartwright. Seeking inspiration, Anthony explores the projects after Brianna's brother Troy and his boyfriend tell them the story of Helen Lyle, who is believed responsible for a killing spree and briefly kidnapping a baby in Cabrini-Green. Stung on the hand by a bee, Anthony meets laundromat owner William Burke, the boy who witnessed Sherman's death. William introduces him to the urban legend of the Candyman, which Anthony tells Brianna and jokingly performs its curse: by saying "Candyman" five times to a mirror, Sherman's spirit will appear and kill the summoner. Inspired by Sherman's death and the Candyman legend, Anthony creates an elaborate art piece titled "Say My Name" for a show curated by Brianna and her colleague Clive, but his work is disparaged by critic Finley Stephens and other attendees. Later that night, Clive and his girlfriend Jerrica unwittingly summon the Candyman, who brutally murders them; Brianna discovers their bodies, triggering childhood memories of witnessing her father's suicide. Anthony compulsively paints gruesome portraits of unknown men, becoming obsessed as he investigates Helen Lyle and her own Candyman research, and has a vision of Sherman's ghost in an elevator. Interviewed by Finley, Anthony goads her into summoning the Candyman herself, and has another vision in a mirror of himself as Sherman. Joining Brianna at a business dinner, he leaves abruptly when he learns Finley has been murdered. Anthony goes to William, who explains that the legend originated in the 1890s with Daniel Robitaille, an artist who had an interracial affair with a white client's daughter. After the daughter claimed Robitaille raped her, he was mutilated and burnt alive. The legend has been renewed for generations with the souls of other murdered innocent black men joining the Candyman "hive"; these are the subjects of Anthony's paintings. Anthony attempts to protect Brianna, but only frightens her with his increasingly erratic behavior. A teenager who attended Anthony's show and her classmates are killed after summoning the Candyman in their school bathroom. Anthony undergoes a physical transformation, spreading from the bee sting on his hand across his entire body. He confronts his mother, Anne-Marie, after visiting a hospital and learning that she lied to him: he was born near Cabrini-Green, and was the baby taken the night Helen died. Anne-Marie admits the Candyman was responsible for the bloodshed blamed on Helen, and the community vowed never to speak his name. Brianna seeks out William, who abducts her to an abandoned church, where Anthony is in a fugue state. Shortly after Sherman's death, William witnessed his return as the Candyman when his sister and her friend summoned him and were killed. William plans to resurrect the Candyman "hive" as a form of retaliation against gentrifiers. Sawing off Anthony's hand and replacing it with a hook, William calls the police to have Anthony wrongfully gunned down as another vengeful spirit to join the hive. Chased into the Cabrini-Green row houses, Brianna stabs William to death with a pen. She is confronted by Anthony, who collapses in her arms and is shot dead by the police. Detaining Brianna in the backseat of a car, the police try to intimidate her into agreeing that Anthony was the killer and that his shooting was justified. Instead, she uses the rearview mirror to summon the Candyman, who appears as Anthony and massacres the police. Swarming with bees, his face transforms to that of Daniel Robitaille, instructing Brianna to "tell everyone" what she has witnessed. The film's end credits feature a shadow puppet montage of members of the growing Candyman hive, including Daniel, Sherman, Anthony Crawford, James Byrd Jr., George Stinney, and Anthony himself.

Ms. Martin, the CEO of Tri-Oceanic Corp., hires geologist Steven Beck to supervise an undersea mining operation for three months. The crew consists of members Glen "Doc" Thompson, Elizabeth "Willie" Williams, Buzz "Sixpack" Parrish, Justin Jones, Tony DeJesus Rodero, Bridget Bowman and G.P. Cobb. While working outside their deep-sea station in a pressure suit, Sixpack discovers a Soviet shipwreck, Leviathan. The crew salvages a safe from Leviathan, finding records detailing the deaths of several crew members as well as a video log from the captain. Sixpack also finds a flask of vodka which he shares with Bowman. Doc and Beck review the captain's video, which describes puzzling medical problems amongst his crew. They also discover that Leviathan was scuttled. The following morning, Sixpack feels sick and Doc discovers lesions along his back. Sixpack dies a few hours later, but Doc and Beck keep it quiet to avoid a panic. Doc checks the crew to confirm no one else is showing Sixpack's symptoms but does not have the chance to examine Bowman. While Beck and Doc confer with Martin on the surface, Bowman begins feeling ill. She finds Sixpack's corpse, which is mutating and growing. When Bowman's hair starts falling out, she realizes the same thing is happening to her. Beck and Doc request emergency evacuation, but Martin reports a severe storm on the surface that will delay evacuation for twelve hours. Doc finds that Bowman has committed suicide. Her body is taken to the station's sick bay, where it merges with Sixpack's. When Doc and Beck discover the mutating bodies, they decide to dump both in the ocean. Just as they are about to "flush" the cadavers, the body bag begins squirming. Believing someone inside may be alive, the crew opens it. The creature inside claws Cobb before they eject it. The team realizes that Leviathan was experimenting on its unwitting crew with mutagens containing piscine DNA. The mutagen was mixed with the vodka that the crew, and later Sixpack and Bowman, drank. The ship was scuttled when the experiment spiraled out of control. A tentacle that was severed when the corpses were ejected mutates into a lamprey -like creature that attacks DeJesus in the kitchen. Jones seals the kitchen's pressure doors and goes for help. He asks Cobb to watch the door, but when he searches for a weapon, the creature assimilates DeJesus and rips its way out of the kitchen. It then grows tentacles that attack the crew. The creature attacks the medical bay, devouring blood and plasma from the cooler. This inspires Beck to use a pint of his blood to attract the monster, then attempt to flush it the same way they did with the Sixpack and Bowman creature. Doc ejects the escape pods so that no one can escape and risk bringing the mutagen to the surface. Beck consults with Martin for emergency evacuation. Martin assures them that they will not be left behind, but that she cannot carry out the rescue because of a hurricane. Cobb's injuries worsen, causing him to mutate and infect Doc. Williams escapes as Beck and Jones try trapping the creature. They escape to another part of the station. The crew tries accessing weather information through the computer, but it is blocked. Williams asks the computer for a financial report from the company and they discover that Tri-Oceanic Corporation has declared them dead, labeling it an accident. The creature damages vital systems, causing the pressure to drop and an implosion to occur. They decide to use their dive suits to escape. The creature attacks them, but is crushed by the lift as Beck escapes. They make it to the surface, which is calm and sunny. As they are met by a Coast Guard helicopter, the first mutant surfaces nearby and tries to take Jones. Jones keeps it from escaping at the cost of his own life and Beck throws a demolition charge into the creature's mouth, causing it to explode. After they are dropped off on a Tri-Oceanic oil drilling platform, the two survivors are greeted by Martin. Martin tells them she believed they would make it, smiling and asking how Beck feels. Beck punches Martin in the face and answers, "Better. A lot better."

Jill and Alan 'Hoaggie' Hoaganraad are on a road trip with their two teenage sons, Maika and Jordan. While hiking, Maika notices two men in the distance watching them before disappearing. While the family picnics by the road, they are interrupted by the two violent drifters, Mandrake and Tubs. The pair robs them at gunpoint and forces them to lie down, but before they leave, Mandrake overhears Maika call Alan 'Hoaggie'. Mandrake suddenly murders Maika and Jordan and abducts the parents after night falls, knocking Jill unconscious and breaking Alan's arm. As Mandrake questions the pair, he reveals that he knows Alan is a teacher and was once an assistant teacher at a group home for troubled boys, one notorious for physical and sexual abuse. Alan guesses correctly that both were enrolled at the school, but he insists that he was completely unaware of the abuse; Mandrake does not believe him and implies that they are driving to the boy's home. When they stop at a gas station, Alan attempts to secretly alert the station attendant; however, Mandrake suspects this and kills the attendant by bludgeoning him with a fire extinguisher. Alan pretends to accidentally hit himself with the door while entering the car but as he kneels next to the car to "recover", he presses a screw into the back left tire. Jill attempts to escape, but is quickly caught and later forced to kneel underneath an overpass. Threatening to shoot her, Mandrake forces Alan to admit that he was aware of all of the abuse, but stopped and reported nothing out of cowardice. Alan relays a story of a young boy who tattooed a swastika on his arm; at roll call, an admin of Jewish background painfully and forcibly scrubbed it from his skin with a nylon brush, which traumatized the rest of the students. Jill is shaken by this admission, and later rebuffs Alan's attempts at contact. When it's clear that Mandrake will not let her go, she escapes from the moving vehicle and then chooses to jump into the nearby river rather than return to her abductors; her fate is left ambiguous. Alan briefly escapes when they stop to replace the tire Alan pressed a nail into, and reaches a car with a group of teenagers. However, Mandrake finds them and convinces them to force Alan out of the car, before murdering all but one, who manages to escape when Mandrake runs out of ammo. With Alan recaptured, they finally reach an old boarding school, presumably where Mandrake and/or Tubs grew up. Walking through the now-abandoned building, Alan admits that he was not just a coward, but also privately believed that the boy with the tattoo deserved his punishment. Believing Mandrake to be that boy, he apologizes for not stepping in. Mandrake reveals that the boy wasn't him. He then shoots Alan in the chest and taunts him, but Alan hits him with a rock and bludgeons him. Mandrake survives, though wounded and disoriented, and tries but fails to kill Alan. Tubs, who Alan had talked to a few times, implying that he only does what Mandrake tells him to, likening that behaviour to still being in a boarding school, arrives and kills Mandrake with the rifle. He leaves the heavily wounded Alan, telling him "I hate this place", which is also carved into a stone behind Alan. Flashbacks reveal that the carving was made by a traumatised boy growing up at that boarding school; whether or not that boy had actually been the tortured one is not explicitly shown. Tubs goes to an undisclosed location and looks out at the rising sun, silently crying.

In the Salton Sea in California, an underwater earthquake causes a crevice to open, releasing prehistoric giant molluscs. A rescue training parachute jump is conducted, but the patrol boat sent to pick up the jumper finds only a floating parachute. One sailor dives in but also disappears. The other sailor screams in terror as something rises from the water. When the patrol boat does not answer radio calls, Lt. Cmdr. John "Twill" Twillinger takes a rescue party out on a second patrol boat to investigate. They find the deserted patrol boat covered in a strange slime; the jumper's body then floats to the surface, now blackened and drained of bodily fluids. Twill takes a sample of the slime to the base lab for analysis, where he teams up with recently widowed Gail MacKenzie and Dr. Jess Rogers. A young couple disappear after going for a swim. U.S. Navy divers investigate and discover a giant egg and the body of one of the victims on the ocean floor. The divers are attacked by a giant mollusc (which looks like a giant caterpillar), which kills one of the divers. The mollusc attacks the boat, but Twill stabs it in the eye with a grappling hook. The egg is taken to the U.S. Navy lab for study and kept under temperature control to prevent it from hatching. The molluscs escape into an irrigation canal system, attacking livestock, a lock keeper, a trysting couple, and others. Navy divers locate a group of molluscs in the canal system, and use explosives to destroy them. In the meantime, Gail is at the lab with her young daughter, Sandy. Worried about the laboratory rabbits being cold in the laboratory’s lowered temperature, Sandy surreptitiously turns up the thermostat. Twill calls the laboratory and gets no answer. He arrives and finds that the hatched mollusc has Gail and Sandy cornered in a closet, where they ran to escape from the monster. He fights it with laboratory chemicals, a CO fire extinguisher and a live steam line until other Navy personnel arrive and shoot the mollusc.

A young boy is setting fire to newspapers in the basement. His name is Mikey and he has a younger sister, Beth, whom he blames for the fire when his foster mother admonishes Mikey. When Mikey is disciplined by his foster mother for starting the fire, he responds by causing Beth to drown in the pool, electrocuting his foster mother while she is in the bath, and bludgeoning his foster father to death with a baseball bat. Mikey avoids suspicion because he is only nine and he tells the police that an intruder killed the family. Detective Reynolds is assigned to the case and he does not suspect Mikey. A psychiatrist recommends that Mikey get fostered as soon as possible. His foster mother's sister is put forward as a prospective foster carer, but she does not want anything to do with Mikey. She states that he was adopted and that it was suspected that he was abused by members of his family. He is then sent to a new family, Neil and Rachel Trenton, who do not know anything about Mikey's past. Presenting himself as an amiable and loving child, his behavior does not raise red flags. He also manifests behavior which is not out of the ordinary in his desire to succeed in a game at school. Mikey then falls in love with his new best friend Ben's older sister, Jessie, who is 10 years older than Mikey. She is not interested in him and is dating a boy named David. In an attempt to make Jessie love him, Mikey kills Jessie's cat and places it under David's car to make it appear as though David was responsible. Tension arises in the relationship but Jessie forgives him. Mikey electrocutes David while he is in a Jacuzzi by kicking the radio in the water. After this fails and he is found out by his foster mother, he fatally stabs her with a glass shard. He kills his school's principal and teacher with a bow and arrow and slingshot when they arrive shortly afterward to investigate their suspicions, and unsuccessfully tries to shoot Jessie with a bow. To avoid being blamed, Mikey fakes his own death. He stages a skeleton of a boy the same age as him taken from his classroom at the dining table and then blows up the house with a gas leak and Molotov cocktail when his foster dad arrives home to find everyone dead around the table. Jessie is told by the authorities that Mikey is dead. Later, Mikey, going by the name "Josh," is adopted by another family.

Syd March is employed by Lucas Clinic, a company which purchases viruses and other pathogens from celebrities, then purposefully infects paying fans who desire a connection with their idols. The company puts a copy protection on its products, which render the pathogens incommunicable after infecting a client. The pathogens supplied by Hannah Geist, Lucas Clinic's exclusive celebrity, are extremely popular. Syd March's colleague, Derek Lessing, is responsible for directly harvesting them from Hannah. To make extra money, Syd steals pathogens from the lab, bypasses the copy protection with a stolen console, and uses himself as an incubator. He then passes the pathogens to Arvid to sell on the black market. Arvid works at Astral Bodies, a celebrity meat market providing meat grown from the cells of celebrities. After Derek is caught smuggling and arrested, Syd is tasked to replace him to harvest a pathogen from Hannah, who has recently fallen ill. After taking a blood sample from Hannah, Syd injects himself with some of her blood. After experiencing the first symptoms, fever and disorientation, he leaves work early. His attempts to remove the virus' copy protection are unsuccessful, and his console breaks down during the process. The next day, Syd awakens from severe delirium to learn that Hannah has died from the unknown disease, and all products harvested from her have skyrocketed in popularity. To fix his console, Syd approaches Arvid, who sets up a meeting with Levine, the leader of the piracy group. Levine offers to fix the console in exchange for samples of Syd's blood, but Syd refuses. Levine restrains Syd and forcibly takes samples from him. Lethal pathogens are not legal to distribute, which only increase demands for the pathogen that killed Hannah. The next day, a severely ill Syd is approached by two men, who drive him to a secret location that houses Hannah. The celebrity, whose death was fabricated to protect her, is barely alive, extremely weak and bleeding from her mouth. Hannah's physician, Dr. Abendroth, reveals the virus infecting them has been engineered with a mechanism to prevent analysis, which broke Syd's console. It is, in fact, a modified version of an illness that Hannah has had before. Abendroth reveals his infatuation with Hannah, showing samples of her skin grafted to his own arm. He derides Syd as "just another fan." Syd returns to the Lucas Clinic, and traces the original strain of the virus to Derek, who sold it to a rival company, Vole & Tesser. Dr. Abendroth discovers that Vole & Tesser patented the modified strain, though their motives remain unclear. Before Syd can proceed further, he is abducted by Levine. Syd is put in a room where his deterioration and death will be broadcast on reality television to sate Hannah's fans, who could not witness her death. As Syd begins to show the final symptoms, he escapes by stabbing Levine in the mouth with a syringe and holding a nurse hostage with his infected blood. After Syd realizes that Vole & Tesser infected Hannah to harvest their own patented pathogen from her, Syd contacts them and negotiates a deal. Some time later, a virtual reality version of Hannah that advertises the "Afterlife" product, coming exclusively from Vole & Tesser. Syd now works for Vole & Tesser, where Hannah's cells have been replicated to form a distorted cell garden from Astral Bodies' celebrity meat technology. Viruses injected into her system are sold. Syd demonstrates a new virus as he sticks a needle into a genetically created arm. Later, while alone, Syd cuts the arm and drinks the flowing blood; it is revealed the arm is in fact Hannah's, as her deformed face and body are shown to be in the Cell Garden chamber.

In 1965, rebellious teenager Heather Fasulo is sent to the boarding school Falburn Academy, run by headmistress Ms. Traverse and located in the middle of the woods. Heather becomes close friends with Marcy Turner, while they are abused by their abusive classmate Samantha Wise. During the night, Heather has a nightmare about a blood-soaked student named Ann and hears voices coming from the woods; she learns the next day that Ann was institutionalized after a suicide attempt. Heather eventually learns to adjust to the school. Ms. Traverse subjects Heather to tests to see if she is "gifted". The girls tell Heather a spooky story about the history of Falburn, which includes three young redheaded sisters who arrived at the school and turned out to be witches, killing the headmistress before leaving to the woods. Heather begins to fight back against Samantha's continued torment. Ann returns from the institution; after Heather finds her rocking in her bed one night, Ann reveals that she is afraid she will be taken by the witches. Heather climbs on a trunk to try and close an open window; a low fog rushes into the room and knocks Heather down, twisting her ankle. The next day, Heather finds Ann's bed empty, her place filled with dead leaves. Heather witnesses the headmistress lying to the police about Ann's disappearance. She tries to talk to Marcy about her suspicions, but Marcy acts strangely; soon after, Heather finds Marcy's bed empty and covered in leaves. Later, she is confronted in the woods by Samantha, who tells her that the school is led by a coven of witches, and that her bullying was intended to drive Heather away to protect her. She also reveals that she has called Heather's father to help her escape and that the school's milk is poisoned. The girls are caught by a school mistress, who takes Samantha away; her body is later found hanging in the cafeteria. Heather tells a police officer about the missing students, but the headmistress claims they simply ran away. Another mistress leads the officer into the woods to find the girls, where he is killed by the living vines of a tree. Heather's parents show up to take her home. On the way home, their car is mysteriously flipped and Heather is knocked unconscious, while her mother is dragged out of the car by a vine. Heather and her father Joe wake up in a hospital. Ms. Traverse has Heather dragged away, then slits her own hand and forces her black blood down Joe's throat, rendering him catatonic. Heather returns to the school, where she drinks the milk, but later vomits it back up, finding tree bark in it. At the hospital, Joe wakes up and vomits up the blood, which also has tree bark in it. He escapes and looks for Heather. That night, Heather begins to hear voices again, and when she attempts to leave, a vine captures her. She awakens wrapped in vines in a large room next to Ann and Marcy, who are also captive. All of the teachers appear and reveal themselves to be witches. Ms. Traverse is their leader, and she explains that their spirits have been trapped in the woods all these years, and they need to inhabit the bodies of young women to escape their imprisonment, with Heather as the centerpiece of her plan since she has the strongest powers. Heather is coerced into carrying out the ritual, and the vines begin to mummify all of the girls in the school. Before the ritual is complete, Joe breaks into the room with an ax and attacks one of the witches before being seized by vines. Heather breaks free and chops all of the witches into pieces. Heather and Joe then leave with all of the girls as the school burns in the distance behind them.

The story of the film is presented in documentary format, with footage of the events punctuated by interviews with people related to them. In the early 1970s, Dr. Henry West (William Mapother) founded the Atticus Institute in rural Pennsylvania, hoping to find evidence that proves supernatural abilities such as ESP are real. Despite the best work of West and his aides, however, every subject that comes to the institute seeming to display such abilities are ultimately proven to be frauds. The team is demoralized in their work by the time Judith Winstead (Rya Kihlstedt) is brought to the institute by her sister Margaret, who is troubled by her disturbing behavior. The tests immediately proves to be no challenge for Judith's incredible power, the team gradually introduces new tests that show her to possess even greater abilities than first imagined. Judith's behavior grows more unstable as her abilities evolve, disturbing West's staff. Bizarre events begin to happen to the aides and their families outside of the institute, which they suspect Judith is somehow influencing, and many of them resign from their positions to escape from her. As the situation escalates, the team seeks help from the United States military; under the influence of military advisors, they conduct new tests that lead to Judith manifesting new abilities such as telekinesis and pyrokinesis. One day, Judith experiences a violent reaction to a spectral photography experiment, and when the images are checked, a cloud-like entity is observed temporarily leaving Judith's body during her convulsions. This leads the team to realize that Judith's powers are the result of demonic possession. With this discovery, the military seizes full control of the institute under a pretext of national security, and the situation spirals completely out of control. Soon, the military decides that Judith's abilities can be utilized as a weapon against the Soviet Union in the Cold War, and they begin conducting increasingly inhumane experiments on Judith against West's objections. Using methods such as electroshock therapy, the military try to tame the demon and force it to cooperate in exercises such as identifying the location of enemy bases, ignoring the effects these tests have on Judith. As these experiments ultimately prove fruitless, the military decides to try removing the demon from Judith by having a priest perform an exorcism while a soldier is connected to Judith. The process shows promise at first, but Judith suddenly lashes out and gravely injures the priest, disconnecting the electrodes attached to her before passing out. As the staff try to reattach the electrodes, Judith experiences a violent seizure while the demon attacks West through the body of the soldier connected to her. An unseen force blasts through the facility, knocking out all present. As the cameras come back online, Judith is now free of the demon's control and restored to her true self, but still tied to a chair in an observation cell. She panics when she sees the carnage around her. The demon enters the room in West's body, having fully consumed his soul, and stands before Judith's cell as she pleads for help. West kills Judith by telekinetically bursting her heart, then calmly exits the room and disappears. The film concludes with a note revealing that Judith's body was buried in an undisclosed location following an autopsy, and her case "remains the only instance of possession officially recognized by the United States government". Dr. West, having "disappeared on October 23, 1976" is revealed to have been declared legally dead in 1982 and his whereabouts unknown for over forty years.

Dr. Lawrence Angelo, a scientist at Virtual Space Industries (VSI), conducts experiments using psychoactive drugs and virtual reality to enhance cognitive performance in a program called "Project 5". Although Angelo's intentions are benevolent, VSI is funded by "The Shop", a clandestine organization seeking military applications for his research. One of his test subjects, a chimpanzee named Rosco, gains enhanced intelligence, warfare training, and increased aggression; he eventually escapes but is killed by the laboratory's security forces. In response, Angelo decides to recruit Jobe Smith, an intellectually disabled gardener, as a new test subject, promising him increased intelligence. Angelo redesigns the treatments to eliminate the "aggression factors" used in the chimpanzee experiments. Not only does Jobe's intelligence improve, but he also develops psychokinesis and telepathy. He continues his training at the lab until an accident forces Angelo to halt the experiment. Sebastian Timms, the project director, monitors the progress and secretly replaces Angelo's new medications with the original Project 5 formula. When Jobe invites his new lover Marnie to the lab for cybersex, he accidentally lobotomizes her. Undeterred, Jobe continues the treatments on his own and begins killing those who mistreated him in the past, as well as Harold Parkette, the abusive father of his 10-year-old friend, Peter. Angelo discovers the drug switch and confronts Jobe, who captures him and reveals his plan to achieve the ultimate stage of evolution by transforming into a being of "pure energy" within the VSI computer mainframe, intending to connect to all the world's computer systems. Jobe vows that his "birth" will be signaled by every phone on Earth ringing simultaneously. The Shop sends a team to capture Jobe, but he uses his newfound abilities to destroy them. Jobe then enters the VSI mainframe, abandoning his physical body and becoming a digital being. Angelo remotely accesses the VSI computer, encrypting its connections to the outside world, thereby trapping Jobe in the mainframe. As Jobe frantically searches for an unencrypted network, Angelo sets bombs to destroy the building. Feeling responsible for Jobe's fate, Angelo enters virtual reality, attempting to reason with him one last time, even if it means dying together. Jobe overpowers Angelo, crucifying his digital form. When Peter enters the building, Jobe realizes the boy is in danger from the bombs. Out of lingering care for Peter, Jobe allows Angelo to escape the mainframe to save the child. Jobe himself escapes through a maintenance line just before the building explodes. Later, Angelo is at home with Peter and his mother, Carla, when the telephone rings. Soon, another phone rings, followed by phones ringing worldwide—Jobe's signal that he has succeeded.

A Russian peasant family is eating dinner when a truck stops in the front yard. The father opens the door of the truck to find a dead woman and two crying infants in the seat next to her. Marie Jones, an American woman, is seen in a Russian hotel room making a call to her daughter; she then goes to meet a local notary, who tells her that she has inherited some property, and that she should visit it. Having been taken to the wooded island, she finds that the house is dilapidated and inhabited by zombie-like creatures, one of whom looks like her. Having attempted to escape, she meets Nikolai, who tells her that they are fraternal twins, adopted separately following the murder of their mother. The house seems to change at random between dilapidation and domestication. Threatened by the zombie-like creatures, Nikolai shoots one of them in the leg, only to find that the wound appears on his own body. He deduces that they are his and Marie's doppelgängers, and that 'what happens to them happens to us'. When Nikolai falls into a hole in the floor while the house is dilapidated, Marie is unable to rescue him because the hole suddenly seals as the house changes to a domesticated state. Marie attempts to escape by rowing across the river. After a lengthy walk on the opposite bank, she happens upon a house, only to find that it is the house she has escaped from, with Nikolai inside. He explains that their father intended to kill them along with their mother when they were babies, and that they cannot leave until he has managed to reunite the family in death. The house reverts to its state on the night of the murder, and they see their father returning home. Nikolai tells Marie that they can escape in the truck along with their mother and their younger selves. While searching for the truck, Marie finds her father's now desiccated body in the barn, and is then pushed into a pseudo-past where she realizes her father and the notary are the same person. She flees his office in the present and runs into her past self as she comes up the steps, and continues fleeing into the sunlight until she finds herself back in the house, this time between the past and the present, where the apparition of her father explains that he has always loved his children and his wife, and could not let them leave him. Marie runs from him and finds Nikolai's body being eaten by boars. When her doppelgänger comes after her, Marie flees to the truck parked outside and drives away. Marie's father's voice comes over the radio, telling her to return and join the family he has created. The bridge that brought her there has been destroyed, and she plunges into the river, drowning. The film ends with Marie's daughter, Emily, explaining that she knew her mother would never return. It has been a long time since her mother left for Russia, and Emily has never had the desire to know what happened to Marie or her parents, breaking the cycle and leaving her abandoned.