In rural Texas, go-go dancer Cherry Darling runs into her mysterious ex-boyfriend El Wray at the Bone Shack, a restaurant owned by brothers J.T. and Sheriff Hague. Meanwhile, the demented Lt. Muldoon and his men make a transaction with chemical engineer Abby for mass quantities of DC2, a deadly biochemical agent. When Muldoon learns that Abby has an extra supply, he attempts to take Abby hostage, causing him to release the gas into the air, mutating most of the town's residents into deformed zombie -like creatures. The infected townspeople are treated at a local hospital by Dr. William Block and his bisexual anesthesiologist wife, Dakota, who is abused by him. Random attacks begin along the highway, causing El Wray and Cherry to crash. In the aftermath, several zombies tear off Cherry's right leg. At the hospital is Tammy, the former lover of Dakota, who Block recognizes. Upon realizing Dakota was about to leave him for Tammy, he stabs Dakota's hands with her anesthetic syringe needles repeatedly, rendering them useless, before locking her in a supply closet. El Wray is detained by Sheriff Hague based on past encounters between the two. As the patients mutate, El Wray leaves the station and arrives at the hospital, attaching a wooden table leg to Cherry's stump. As El Wray and Cherry fight their way out of the hospital, Dakota manages to escape in her car. Meanwhile, Block becomes infected along with others, while Cherry and El Wray take refuge at the Bone Shack. Dakota retrieves her son Tony and takes him to her estranged father, Texas Ranger Earl McGraw. Tony accidentally shoots himself while waiting in the car. (Following a "missing reel" segment) Dakota, Earl, Cherry's former boss Skip, and Tony's crazed babysitter twins arrive at the Bone Shack. With Hague badly injured, the group decides to flee to the Mexican border, before being stopped by a large mass of zombies. Muldoon's men arrive, killing the zombies before arresting the group. Abby tells them that the soldiers are stealing the gas supply because they are infected and constant inhalation of the gas delays mutation. They also learn that some of the population is immune, hinting at the possibility of a cure. As Cherry and Dakota are taken away by two soldiers, the others defeat the guards. J.T. sustains a gunshot wound in the process while the group searches for Muldoon. When he is found by El Wray and Abby, Muldoon explains that he killed Osama bin Laden before he and his men were infected and were ordered to protect the area before being killed by Abby and El Wray. Meanwhile, Cherry is held at gunpoint and forced to dance by a soldier who threatens to rape her. Eventually, she breaks her wooden leg across his face and stabs him in the eye. Dakota, after realizing that her hands have regained feeling, uses her syringe launcher to subdue another soldier. El Wray and Abby arrive to rescue Cherry and Dakota; El Wray replaces Cherry's broken wooden leg with an assault rifle and grenade launcher. J.T. decides to stay behind to detonate explosives to eliminate the remaining zombies while the others flee. The survivors make plans to escape by stealing helicopters after fighting through a large group of zombies, but Abby gets his head blown apart by a ballistic missile in the process. An infected Block attacks Dakota but is shot dead by Earl. While saving Cherry from a zombie, El Wray is fatally wounded. Cherry, now sporting a minigun leg, leads survivors to the Caribbean beach at Tulum, where they start a peaceful new society during a worldwide zombie outbreak. It is also revealed that Cherry has given birth to her and El Wray's daughter. In a post-credits scene, Tony is sitting on the beach at the survivor's "base" playing with his turtle, scorpion, and tarantula.

Technicians at a secret underground facility prepare for an annual ritual designed to save humanity from extinction. Similar operations around the world stage elaborate sacrificial scenarios based on local horror traditions. Most have already failed this year, and when a Japanese operation unexpectedly collapses, the American team finds they are humanity's last hope. Five college students set out for a weekend getaway at an isolated cabin owned by the cousin of Curt Vaughan, a confident athlete. Accompanying him are his girlfriend Jules, Dana, Holden, and Marty, an eccentric but perceptive stoner. Although the group appears ordinary, unseen technicians are already manipulating their environment. Chemicals pumped through vents subtly alter the students' moods and behavior, nudging them into familiar horror-movie roles: the athlete, the scholar, the fool, the virgin, and the promiscuous party girl. Once inside the cabin, hidden cameras monitor the friends as they explore, while technicians bet on which monsters the group will accidentally unleash. The students discover strange relics and artifacts in the cellar. Dana reads aloud from an old diary belonging to Patience Buckner, whose sadistic family once lived on the property. Her words awaken the Buckners as violent undead killers. Manipulated by chemicals released into the woods, Curt and Jules wander outside to have sex where Jules is brutally murdered by the zombie Buckners. Curt barely escapes. Marty discovers the surveillance equipment hidden throughout the cabin but is attacked while trying to warn the others. The survivors attempt to flee but the facility blocks their escape with collapsing tunnels and sealed roads. Curt attempts a dramatic motorcycle jump across a ravine, crashes into an invisible force field and falls to his death. Attempting to escape in an RV, Holden is killed and the vehicle crashes into the lake. Dana struggles ashore, only to be cornered by one of the Buckners. At the facility, the technicians celebrate, believing the ritual is nearly complete. Their relief is interrupted when Marty suddenly reappears, rescues Dana, and leads her to a hidden elevator connected to the underground complex where the pair uncover the horrifying truth. The entire cabin ordeal has been orchestrated as a ritual sacrifice to appease the "Ancient Ones", colossal subterranean beings capable of destroying the world. The objects in the cellar determine which monsters are released upon the victims, and the chosen victims themselves are forced into symbolic archetypes required by the ritual. When security forces corner Dana and Marty, they unleash imprisoned werewolves, ghosts, giant snakes, mutant killers, and countless other horrors. The technicians who coldly manipulated the victims are massacred in gruesome fashion. Dana and Marty reach an ancient temple beneath the facility, where the director explains the sacrifices must occur in sequence, with the "virgin" dying last or surviving. Since Marty, the designated fool, unexpectedly survived, the ritual remains incomplete. The director urges Dana to kill him and save humanity. A werewolf mortally wounds Dana before she can decide. Marty kills the creature, and together they realize they no longer believe humanity deserves saving through endless cycles of ritual murder. Accepting the consequences, they share a final moment together as the temple collapses. One of the Ancient Ones rises, bringing about the end of the world.

In the year 2678, the spaceship Hunter-Gratzner is struck by micrometeoroids that penetrate the hull, killing the captain and sending it off course toward a nearby planet. First Officer Owens and docking pilot Carolyn Fry attempt an emergency landing. As the ship descends uncontrollably, a panicked Fry prepares to jettison the passengers held in cryostasis to save herself, but Owens intervenes. The ship crash-lands, killing Owens and most of the passengers. The survivors include Fry; Imam Abu al-Walid, escorting three young students (Ali, Hassan and Suleiman) to New Mecca; a teenage boy named Jack; prospectors Shazza and Zeke; wealthy merchant Paris; law enforcement officer William J. Johns; and his prisoner, the dangerous and enigmatic criminal Richard B. Riddick, who escapes in the confusion. While searching for him across the sun-scorched and seemingly barren planet, the group discovers an abandoned geological research settlement with a nonfunctional dropship. When Zeke goes missing, the survivors suspect Riddick. However, Fry investigates a nearby underground cave where she is attacked by aggressive creatures and narrowly escapes. Johns recaptures Riddick and offers to release him in exchange for helping them escape the planet. While exploring the settlement, one of the students, Ali, disturbs a cluster of juvenile creatures, which devour him before retreating underground to avoid the sun, revealing a fatal vulnerability to light. Using an orrery, Fry discovers that a total eclipse—occurring every twenty-two years—is imminent. Once darkness falls, the creatures will emerge to hunt, explaining the fate of the previous settlers. As tension builds, both Johns and Riddick try to win Fry to their side: Fry recounts Riddick's cold pragmatism, while Riddick exposes Johns as a morphine-addicted bounty hunter who had refused to use his drugs to ease Owens' agonizing death. The group races back to the Hunter-Gratzner to retrieve power cells for the dropship, but the total eclipse begins, unleashing thousands of flying creatures that kill Shazza. The survivors take shelter inside the Hunter-Gratzner, but the creatures breach it and devour Hassan. Realizing they must reach the dropship, they enlist Riddick—whose surgically enhanced eyes grant him night vision—to guide them through the darkness. Armed with available and improvised light sources, the group sets out. When the group reaches a narrow canyon teeming with creatures, Paris panics, runs, and is killed. Riddick reveals that Jack is actually a girl disguising herself as a boy, and her menstrual blood is attracting the creatures. In private, Johns suggests to Riddick that they wound Jack and leave her behind as a distraction. Riddick pretends to agree, then attacks Johns—injuring him and leaving him to be killed by the creatures. At Riddick's urging, the remaining group sprints through the canyon as the creatures begin cannibalizing one another. After reaching the other side, rain begins to fall, extinguishing their improvised torches. Suleiman is killed in the ensuing attack. Riddick initially moves on alone but ultimately returns to fight off the creatures and save Jack. He hides Fry, Abu al-Walid, and Jack in a cave, then sets out to retrieve the dropship. Suspicious, Fry follows and finds him preparing to take off and abandon them. Fry pleads with Riddick to help her save the others, but he urges her to escape with him instead. Guilt-ridden over her earlier attempt to sacrifice her passengers, she refuses, admitting she would now die to protect the others. Together, they rescue Abu al-Walid and Jack (with small, bioluminescent native lifeforms), but Riddick is cornered and wounded by the creatures. Fry returns to save him, but she is fatally stabbed by one of the creatures and carried off. Riddick returns to the ship but delays takeoff, allowing the creatures to gather around it before using the engines to incinerate as many as possible. Once in space, Jack asks what they should tell the authorities about him; he tells them that Riddick died on the planet.

Workers building an extension to the London Underground at Hobbs End dig up a skull. Palaeontologist Dr. Matthew Roney identifies it as a five-million-year-old apeman, more ancient than previous finds. Part of a metallic object is uncovered nearby. Believing it to be an unexploded bomb from the London blitz, they call in an army bomb disposal team. Meanwhile, Professor Bernard Quatermass learns that his plans for the colonisation of the Moon are to be taken over by the military, who want to establish missile bases in space. Colonel Breen is assigned to Quatermass's British Experimental Rocket Group. When the bomb disposal team call for Breen's assistance, Quatermass accompanies him to the site. When another skull is found within a chamber of the "bomb", they realise that the object itself must also be five million years old. Noting the ship's imperviousness to heat, Quatermass suspects it is of alien origin. Roney's assistant, Barbara Judd, goes to the site with Quatermass. She becomes intrigued by the name of the area, recalling that "Hob" is an old name for the Devil. A policeman mentions a legend that the bombed-out house opposite the station is haunted. All three go there to investigate. Quatermass and Barbara later find historical accounts of hauntings and other spectral appearances going back centuries, coinciding with disturbances of the ground around Hobbs End. A member of the bomb disposal team witnesses a spectral apparition of Roney's apeman appearing through the object's wall. An attempt to open a sealed chamber in the object using a Borazon drill fails. Later, however, a small hole is seen. The hole widens to reveal the corpses of insectoid creatures with horned heads. An examination of their physiology suggests that they came from Mars. They resemble images of the Devil; Quatermass believes that the spaceship is the source of the spectral images and disturbances. They reveal their findings to the press. Quatermass theorises that the occupants of the spaceship came from a dying Mars. Unable to survive on Earth, they sought to preserve part of their race by creating a colony by proxy, by enhancing the intelligence of and imparting Martian faculties to the indigenous primitive hominids. Quatermass theorises that the insectoids used medical and surgical techniques that were more advanced than those on present-day Earth. These apemen's descendants evolved into humans, retaining the vestiges of Martian influence buried in their subconscious. Breen thinks that the "alien craft" is Nazi propaganda designed to sow fear among Londoners. A government minister believes Breen and decides to unveil the spaceship at a press conference. The drill operator, Sladden, is later overcome by a psychic force and flees. His mind unleashes telekinetic energy displays, disrupting people and property. He comes to rest in a church. Before recuperating, Sladden has a vision of insect creatures under an alien sky. Sladden sees himself as one of them and feels that he has to flee to save his life. At Hobbs End, Quatermass brings a machine which taps into the primeval psyche. While trying to replicate the circumstances under which Sladden was affected, he notices that Barbara has fallen under the spaceship's influence. Using the machine, he records her thoughts. Quatermass presents the recording to the minister and other officials. It shows Martians engaged in what he interprets as a genocidal race purge, to cleanse the Martian hives of all mutations. The minister and Breen dismiss the recording. A power line later is dropped within the craft, giving it a jolt of electrical energy. The effect and range of the spaceship's influence on Londoners increases; they go on a rampage, attacking all those perceived as different, with deadly telekinetic displays of energy. Breen is drawn towards the spaceship and killed by the energy emanating from it. Quatermass falls under the alien control too, but is snapped out of it by Roney, who is unaffected. A small portion of the population turns out to be immune. The psychic energy intensifies, ripping up streets and buildings, while a spectral image of a Martian resembling the image of the Devil of legend towers above London. Recalling stories about how the Devil could be defeated with iron and water, Roney theorises that the Martian energy can be discharged into the earth. Roney climbs a building crane and swings it into the image. The crane bursts into flames as it discharges the energy, killing Roney. The image and its effects on London disappear.

A man named Goreng awakens in a cell numbered 48. His cellmate Trimagasi explains that they are in a tower-style holding facility. Once per day, food arrives on "the platform" that lowers from level 0, stopping for two minutes on each level. Prisoners can only eat while the platform is stopped on their level, and are subjected to fatal temperatures if they keep any food. Prisoners are randomly reassigned to a new level each month. Trimagasi reveals that when assigned to level 132, he and his former cellmate cannibalized someone. One day, a woman named Miharu rides down the platform, whom Trimagasi explains regularly descends the pit to search for her child. Goreng explains that he volunteered to spend six months in the facility in exchange for a diploma, while Trimagasi confides that he is serving a year-long sentence for manslaughter. The following month, they are reassigned to level 171. Trimagasi ties up Goreng and explains his plans to feed himself using Goreng's flesh. When he begins cutting into Goreng's leg, Miharu arrives, attacks Trimagasi, and frees Goreng, who kills Trimagasi. Encouraged by Miharu, Goreng eats Trimagasi's flesh and subsequently becomes haunted by hallucinations of Trimagasi. The next month, Goreng wakes on level 33 with a woman named Imoguiri and her dog, Ramesses II. Imoguiri was the administration official who interviewed Goreng before sending him to the pit, having admitted herself after being diagnosed with terminal cancer. Imoguiri only eats every other day, letting Ramesses II eat on the days that she does not, and tries unsuccessfully to convince the pair below them to ration their food. One day, Miharu arrives injured. Goreng and Imoguiri nurse her back to health. That night, Goreng breaks up a fight between Miharu and Imoguiri to then discover that Miharu has killed Ramesses II. After Miharu leaves, Goreng mentions her child to Imoguiri, who says there are no children in the pit and Miharu came alone. The following morning, Goreng wakes to find that they have been reassigned to level 202 and that Imoguiri has hanged herself. He consumes her flesh, plagued with hallucinations of his former cellmates. The next month, Goreng is assigned to level 6. His new cellmate, Baharat, is a religious man who has been attempting to escape the pit for months. Estimating that there are 250 levels, Goreng convinces Baharat to ride the platform down with him and ration the food. They forbid anyone on the first fifty levels to receive any, arguing that they get to eat every day, and fend off those who defy them. Fellow prisoner Sr. Brambang advises them that civility is more effective than violence and convinces them to send a symbolic message to the administration by leaving a single panna cotta untouched. As they descend further, they hand out portions to the prisoners, attacking those who refuse to cooperate. They encounter Miharu being attacked and try to save her, but she is killed and they are both left severely injured. Goreng and Baharat continue to descend, eventually stopping at level 333, where Goreng notices a child whom he deduces is Miharu's daughter. They get off the platform, letting it continue downward, and reluctantly feed the girl the panna cotta. That night, Baharat shakes Goreng awake and tells him, "The girl is the message." Goreng awakens, revealing this encounter to have been a dream, and finds that the real Baharat has bled to death. Goreng and the girl ride the platform to the very bottom level. Goreng once again hallucinates Trimagasi, who encourages him to get off the platform. Goreng insists that he has to ride the platform back up to the top, as he is the bearer of the "message," but Trimagasi replies, "The message requires no bearer." Goreng gets off the platform and the two walk away, watching as the child ascends.

In 1967, Edward Jessup is a Columbia University psychopathologist studying schizophrenia. He thinks that "our other states of consciousness are as real as our waking states." He begins experimenting with sensory deprivation using a flotation tank, aided by like-minded researchers, Arthur Rosenberg and Mason Parrish. At a faculty party, he meets fellow "whiz kid" and his future wife, Emily. Over a decade later, Edward is a tenured professor at Harvard Medical School. He and Emily have two daughters and are on the brink of divorce when they reunite – for the first time in seven years – with the couple who had first introduced them. When Edward hears about the Hinchi tribe, whose members experience shared hallucinatory states, he decides to travel to Mexico in order to participate in their ceremony. During the climb up into the Hinchi hill country (a plateau covered in spectacular mushroom-shaped ventifacts), Edward is told by his guide, Eduardo Echeverria, that the Hinchi use in their ceremonies a potion containing the sacred mushroom Amanita muscaria and the shrub sinicuiche, which they are collecting for next year's ceremonies. The tribe calls sinicuiche by a Hinchi name meaning "first/primordial flower" in recognition of the deep memory states which it can evoke. An indigenous elder ("the brujo ") is seen with a root in his hand, which he asks Edward to hold, before cutting Edward's hand in order to add drops of blood to the mixture he is preparing. Immediately after consuming the mixture, Edward experiences bizarre, intense hallucinations, including one of the petrifaction and subsequent erosion by blown sand of Emily and himself. The following morning, Edward leaves the Hinchi plateau under a cloud, having killed, while in his intoxicated state, a large specimen of the Hinchi's sacred monitor lizard. He returns to the U.S. with a sample of the Hinchi potion for analysis by his colleagues and further self-experimentation and continues taking it in order to take his exploration of altered states of consciousness to a higher level. When toxic concentrations of the substance make increased dosage dangerous, Edward returns to sensory deprivation, believing it will enhance the effects of the substance at his current dose. Repairing a disused tank, he uses it to experience a series of increasingly drastic visions, including one of early Hominidae. Monitored by his colleagues, Edward insists that his visions have "externalized". Emerging from the tank, his mouth bloody, frantically writing notes because he is unable to speak, he insists on being X-rayed before he "reconstitutes." A radiologist inspecting the X-rays says they belong to a gorilla. In later experiments, Edward experiences actual, physical biological devolution. At one stage, he emerges from the isolation tank as a feral and curiously small-statured, light-skinned caveman, going on a rampage in town and breaking into a zoo before returning to his natural form. In the final experiment, he experiences a more profound regression, transforming into an amorphous mass of conscious, primordial matter. An energy wave released from the experiment stuns Edward's colleagues and destroys his tank. Emily recovers and finds a swirling maelstrom where the tank had been. She searches in the vortex for Edward, finding him as he is on the brink of becoming a non-corporeal energy being that will vanish from reality if this transformation reaches its conclusion. His friends bring Edward home, hoping that the transformations will end. Watched over by Emily, Edward begins to regress uncontrollably, the transformations no longer requiring the intake of "first flower" or sensory deprivation. Urging Edward to fight the change, Emily grabs his hand, being enveloped by the primordial energy emanating from him. The sight of Emily apparently being consumed by the energy stirs the human consciousness in Edward's devolving form. He fights the transformation off by banging repeatedly into the hallway wall and returns to his human form. Edward then grabs Emily's form, and she returns to normal. The movie ends with the two on the floor in a nude embrace as Edward tells Emily that he loves her, which she had longed to hear him say.

The film begins with a reenactment of the gruesome act of cannibalism described by the prosecuting attorney during Alferd Packer's 1883 trial. During this sensationalized account, a haggard Packer repeatedly insists that was not how it happened. During a break in the trial, Packer is enticed by journalist Polly Pry to tell his side of the story, which he proceeds to do, via flashback beginning with his horse Lianne galloping in a field. In 1873, Packer was part of a group of miners in Bingham Canyon, Utah who hear of new prospects in Breckenridge. Together, the small group decide to travel together into Colorado Territory. Packer is appointed as the replacement for the original guide, since he claimed knowledge of the area. He and Lianne set off on what Packer estimates will be a three-week journey with a party of five miners: Shannon Wilson Bell, James Humphrey, Frank Miller, George Noon and Israel Swan. Four weeks later, while attempting to visit Provo for supplies they become convinced they are lost. They are given local warning them of impending doom awaiting them in the mountains. Finally arriving in Provo, they run into a group of three fur trappers bound for Saguache; O.D. Loutzenheiser, Preston Nutter, and their diminutive leader, Jean "Frenchy" Cabazon. The trappers despise the miners, whom they contemptuously call "diggers", yet seem to like Packer's Arabian horse, telling Packer that she's a "trapper horse". The next day, Packer wakes up to discover his horse Lianne is missing. The men attempt to cross the Green River near the Utah border. Eventually, after a disastrous crossing of the Colorado River the Packer party is spotted by two " Nihonjin " Indians. They are taken back to the tribe's encampment near Delta where the chief warns them of a winter storm, allowing them to wait it out with the tribe. Packer's party also find the trappers camping out with the tribe, a small altercation breaks out over Lianne, whose feedbag Packer finds in their possession. In the present time, Packer is sentenced to death by hanging, with his execution to occur in Lake City. That night, Polly reveals her growing affection for him through song. The next day, Polly visits Packer once again in prison, where he continues his story. The men set out in the wilderness and begin to suspect that Packer is really only interested in following the trappers to find his horse. They soon run out of food, resorting to eating their shoes as they become lost in the snow-covered Rocky Mountains. An optimistic Swan sings about building a snowman; Bell shoots him in the head out of frustration. The men discuss their dire situation that night over the fire, speaking of the cannibalism that the Donner Party had to resort to in California. They decide to consume the body of their dead companion as Miller cuts up Swan's body, and only Bell refuses to partake in the cannibalism. After a few more days, the party loses hope, which leads to talk of sacrificing one of their own. Packer convinces them for one more chance for a scouting trip, but when he returns, Bell has killed the others, claiming they planned to kill and eat him after Packer left. Packer is forced to throw a cleaver at Bell, seemingly killing him. He is then forced to cannibalize the others to wait out the rest of the winter. Arriving in Saguache sometime later, Packer finds Lianne, who has taken to Cabazon, upsetting Packer. The sheriff of Saguache, suspicious of Packer arriving without the rest of his party, eventually finds out the fate of the other members and attempts to arrest Packer for cannibalism at a saloon. A bar-fight between Packer and the trappers occurs, which Packer wins after brutally attacking Cabazon's groin using fighting techniques he learned from the Nihonjin chief, leaving Cabazon incapacitated. Following this, Packer attempts to flee to Wyoming, only to later be arrested there and brought back to Colorado to await judgment. However, he is saved at the last minute by Polly, who arrives on the scene with Lianne. Meanwhile, Cabazon, wants revenge against Packer for their fight in Saguache. The Nihonjin chief saves Packer by cutting his rope with a katana before beheading Cabazon. Packer, seeing that Polly brought back Lianne, he realizes he does not need her anymore and chooses Polly, the two kiss, only to be frightened by a still-alive but badly maimed Bell.

One night, Caleb Colton, a young man in a small Oklahoma town, meets an attractive young drifter named Mae. Just before sunrise, she bites him on the neck and runs off. The rising sun causes Caleb's flesh to smoke and burn. Mae arrives with a group of roaming vampires in an RV and takes him away. The most psychotic of the vampires, Severen, wants to kill Caleb but Mae reveals that she has already turned him. Their charismatic leader, Jesse Hooker, reluctantly agrees to allow Caleb to remain with them for a week to see if he can learn to hunt and gain the group's trust. Caleb is unwilling to kill to feed, which alienates him from the others. To protect him, Mae kills for him and then has him drink from her wrist. Jesse's group enters a bar and kills the occupants. They set the bar on fire and flee the scene. All except Mae want to kill Caleb after he endangers them by letting the only living occupant escape, but after Caleb endangers himself to help them escape their motel room during a daylight police raid, Jesse and the others are grateful and temporarily mollified. A camaraderie commences, with Caleb asking Jesse how old he is and Jesse responding that he " fought for the South " (during the American Civil War), making him about 150 years old (Severen had earlier suggested he and Jesse started the Great Chicago Fire of 1871). Meanwhile, Caleb's father has been searching for Jesse's group. A child vampire in the group, Homer, meets Caleb's sister, Sarah, and wants to turn her into his companion, but Caleb objects. While the group argues, Caleb's father arrives and holds them at gunpoint, demanding that Sarah be released. Jesse taunts him into shooting him, then regurgitates the bullet before wrestling the gun away. In the confusion, Sarah opens a door, letting in the sunlight and forcing the vampires back. Burning, Caleb escapes with his family. Caleb suggests they try giving him a blood transfusion. The transfusion unexpectedly reverses Caleb's transformation. That night, the vampires search for Caleb and Sarah. Mae distracts Caleb by trying to persuade him to return to her while the others kidnap his sister. Caleb discovers the kidnapping and his tires slashed but gives chase on horseback. When the horse shies and throws him, he is confronted by Severen. Caleb commandeers a tractor-trailer and runs Severen over. The injured vampire suddenly appears on the hood of the truck and manages to rip apart the wiring in the engine. Caleb jackknifes the vehicle and jumps out as the truck explodes, killing Severen. Seeking revenge, Jesse and his girlfriend, Diamondback, pursue him but are forced to escape in their car as dawn breaks. Attempting to save Sarah, Mae breaks out of the back of the car with her. Mae's flesh begins to smoke as she is burned by the sun but she carries Sarah into Caleb's arms, taking refuge under his jacket. Homer attempts to follow, but as he runs he dies from exposure to the sun. Their sunproofing ruined, Jesse and Diamondback also begin to burn. They attempt to run Caleb and Sarah over but fail, dying as the car blows up. Mae awakens later, her burns now healed. She too has been given a transfusion and is cured. Mae says she is afraid, and Caleb pulls her into a hug to comfort her as the film ends.

Lifelong vegetarian Justine begins her first semester at veterinary school, the same one her older sister Alexia is attending and where their parents met. On her first night, she meets her roommate Adrien, who claims he's gay, and they are forced to partake in a week-long hazing ritual, welcoming the new students. They are brought to a party, where Alexia shows Justine old class photos of students bathed in blood, including one with their parents. The next morning, the new class is splattered with blood and is forced to eat raw rabbit kidneys. Justine refuses because of her vegetarianism, but Alexia forces her to eat one. Justine leaves with Adrien and later discovers an itchy rash all over her body. She consults a doctor, who diagnoses her with food poisoning and gives her cream for the rash. The next day, Justine begins having cravings for meat, which makes her feel ashamed. After a failed attempt to steal a burger from the cafeteria, she and Adrien take a late-night trip to a gas station so no one will see her eating meat. Unsatisfied, she eats raw chicken in the morning, and later throws up a long bundle of her own hair she had been chewing on. That night, Alexia attempts to give her a bikini wax, but when Alexia tries to cut the wax off with sharp scissors, Justine kicks her away and Alexia accidentally cuts off her own finger. Alexia faints, and Justine picks up the finger, tastes the blood, and starts eating it. Alexia wakes up to find Justine doing this but later tells their parents that her dog, Quicky, ate it. The next morning, Alexia takes Justine to a deserted road, where Alexia jumps in front of a car, causing the two people in it to crash into a tree. Alexia starts eating one of the passengers so that her sister will "learn"; Justine is dismayed. Despite this, Justine's craving for human meat grows and she starts lusting after Adrien. That night, she arrives at a party, where paint is thrown at her as part of another hazing ritual and she is forced to make out with a boy. While kissing, Justine bites the middle of his bottom lip off, leaving the other party guests shocked and disgusted. Justine returns to her dorm and takes a shower, where she picks a chunk of his lip out of her teeth and eats it. Justine confides in Adrien and they end up having sex, during which Justine tries to bite Adrien but instead bites her own arm until it bleeds profusely, seeming to orgasm while doing so. At another party, Justine becomes extremely intoxicated and Alexia takes her to the morgue. The next day, everyone in school stares at Justine, some avoiding her. Adrien shows her a video where Justine is crawling on all fours, attempting to take a bite out of the arm of a corpse as Alexia eggs her on, to boos and cheers from a crowd of watching party guests. Justine confronts Alexia and fights her, eventually biting each other until they are pulled apart by other students. Justine helps Alexia up, and they walk each other back to their dorms. The next morning, Justine wakes up in bed with Adrien and notices she is covered in blood. She pulls off the blankets, finding Adrien dead with most of his right leg eaten and a stab wound in his back. Justine then sees a bloody Alexia slumped on the floor. Justine is initially furious that Alexia killed Adrien but then cleans Alexia and herself up in the shower. Alexia is imprisoned for the murder of Adrien, and Justine is sent back home. There, Justine's father tells her that what happened is neither hers nor Alexia's fault. He explains that when he first met their mother, he could not understand why she did not want to be with him. Her father says he finally realized when they kissed the first time, indicating a scar on his lip. He then opens his shirt, revealing scars and missing chunks of his chest, and assures Justine that she will find a solution.

The film opens and follows a young man, Martin, traveling on an overnight train from Indianapolis to Pittsburgh. Martin sedates a woman with a syringe full of narcotics, rapes her, slices her forearm with a razor blade, then drinks her blood, allowing her to slowly bleed to death. The next morning, he is met at the train station by his elderly cousin, Tata Cuda, who escorts him to a second train destined for Braddock, Pennsylvania. Martin claims to be much older than his appearance would suggest. He has romantic monochrome visions of religious icons, vampiric seductions, and torch-carrying mobs, but whether these are memories or fantasies is not specified. Cuda has reluctantly agreed to give Martin room and board alongside his granddaughter, Christina. Cuda is a Lithuanian Catholic who treats Martin like an Old World vampire, referring to him as " Nosferatu." He tries unsuccessfully to repel Martin with strings of garlic and a crucifix. Martin mocks these attempts. Christina is also highly skeptical and critical of Cuda's beliefs, and thinks Martin should receive psychiatric treatment. Cuda warns that if Martin murders anyone in Braddock, he will stake him through the heart. Martin seeks advice from a local radio disc jockey, who dubs him "The Count." He rejects many common perceptions about vampires, saying there is no "magic stuff." The DJ's listeners consider Martin to be a hit. Martin gets a job at Cuda's grocery store delivering groceries to customers. One of his customers, Abby Santini, a depressed housewife, becomes taken with Martin. Martin phones the radio show host to describe his infatuation with Abby and senses that she wants to have sex with him. Martin confides that he has never had sex with a woman who was awake. One day, unbeknownst to his family, Martin goes to Pittsburgh and targets a woman he sees at a grocery store. Believing her to be alone while her husband is away on business, he breaks into her house but finds her in bed with a lover. After a series of struggles, Martin kills and feeds on the man instead of the woman, then drugs and rapes the woman before leaving the scene. After Sunday church, Cuda brings home Father Howard, asking about the possibility of exorcism and demon possession. Father Howard calls Father Zulemas at Cuda's request. Together, Cuda and Zulemas confront Martin and attempt to perform an exorcism on him. At this point, Martin has a vision of people trying to exorcise him, then fleeing. Martin then escapes from Cuda and Zuelmas himself. Later that night, Martin terrorizes Cuda in a playground, donning a cape and false fangs. When Cuda attempts to strike him with his walking cane, Martin removes his teeth and makeup, stating, "It's just a costume... It's only a costume," then drifts away into the night. Christina, becoming increasingly frustrated by her disagreements with Cuda, ultimately moves out of his house to live with her boyfriend Arthur and bids Martin goodbye. Later, Martin has sexual intercourse with Abby and they begin an affair which lessens his appetite for blood. Worried about experiencing withdrawal, Martin attacks a pair of homeless derelicts and narrowly escapes the police. Upon returning to Braddock, he visits Abby only to discover that she has committed suicide by cutting her wrists in a bathtub. Cuda, who has learned of Abby's death, believes Martin to be her killer and fatally stakes him through the heart before burying him in a backyard flower bed. Radio callers inquire and speculate about "The Count" while Cuda places a small crucifix atop Martin's grave.

True crime writer Ellison Oswalt experienced success due to his debut book presenting new evidence that led to the perpetrator's capture. Following the failure of his subsequent works, he moves to Chatsford, Pennsylvania with his family. Unbeknownst to Ellison's wife Tracy and their children, 12-year-old Trevor and 7-year-old Ashley, the previous homeowners, the Stevenson family, were murdered by hanging. Hoping to revitalize his career, Ellison intends to research the Stevensons' murders and the subsequent disappearance of their youngest child, 10-year-old Stephanie. In the attic, Ellison finds a box containing a scorpion, a projector, and film reels labeled as home movies. The footage displays families being murdered in various ways, seemingly by the camera operator. Ellison contemplates giving the videos to the police, but, excited at what they could contribute to his career, ultimately decides to keep and study them. Ellison notices a mysterious cultic symbol and a strange figure in the films. He matches one reel to the 1998 murder of the Miller family in St. Louis and the disappearance of their 13-year-old son Christopher. While investigating noises in the attic one night, Ellison finds a king snake inside the film reels' canister lid and childlike doodles of the killings, featuring a figure called "Mr. Boogie." After he falls through the ceiling, emergency services are called, including a deputy who enthusiastically agrees to help Ellison, jokingly accepting the nickname "Deputy So-and-So." Ellison later encounters a Rottweiler in the garden, which flees. Consulting the deputy, Ellison learns that the murders took place in different cities at different times, beginning in 1966, after which a child from each family disappeared. Before moving to Chatford, the Stevensons lived in the Millers' former house. Ellison consults occult specialist Professor Jonas about the symbol in the films, which Jonas links to pagan Babylonian god Bughuul, who is said to lure children into his realm and consume their souls. Jonas suspects the murders are part of a cult initiation rite rather than the work of a single murderer. Ghost children invisible to Ellison begin to haunt the house. Trevor begins experiencing night terrors, and Ashley paints Stephanie on the walls, claiming that Stephanie has been talking to her; Tracy is furious that Ellison moved them into the site of a crime without her knowledge. One night, Ellison finds the missing children in the attic, watching one of the films. Bughuul appears onscreen before physically appearing before Ellison. Ellison destroys the camera, projector, and reels, and moves the family back to their old home. Jonas sends Ellison images associated with Bughuul, including the mysterious symbol and a scorpion, snake, and dog. Early Christians believed that images of Bughuul created a gateway for him to enter the mortal world and possess children who see these images. Ellison finds the projector and reels, undamaged, in his attic, along with a new reel labeled "Extended Cut Endings". The deputy informs Ellison that he has determined the pattern – after a family is murdered, the next family to move in becomes the next victims, but are only killed after fleeing; the hauntings provide incentive. Ellison realizes that by moving again, he has placed himself and his family in danger. The "Extended Cut" depicts the missing children entering the frame following each murder, revealing them as the perpetrators of the killings under the influence of Bughuul – "Mr. Boogie." Feeling lightheaded, Ellison notices green residue in his coffee mug and finds a note from Ashley reading "good night, daddy" before losing consciousness. He awakens to find himself, Tracy, and Trevor bound and gagged. The possessed Ashley approaches with the camera and proclaims she will make Ellison "famous again" before dismembering them with an axe, then using their blood to paint pictures and Bughuul's symbol on the walls. She doodles their corpses on the lid of the film reel box as footage of her murders plays on the projector. Bughuul appears, claims Ashley, and walks into the film with her, presumably consuming her soul. Ashley's reel joins the box of films in the Oswalt family's attic, titled "House Painting '12." In a final jump scare, Bughuul's face suddenly appears onscreen.

Annie Marshall runs out of her house but denies that she needs help to onlookers. She gets into her car and drives away. That night, she sits alone on a beach and when her parents call, she tells them she loves them. In the morning, her mutilated corpse remains on the beach. Carefree college student Jay Height goes to a movie with her boyfriend Hugh. Hugh points out a girl in a yellow dress, whom Jay says she cannot see. Unnerved, Hugh asks that they leave. Later, Hugh and Jay have sex for the first time in his car, after which he incapacitates her with chloroform. Jay wakes up tied to a wheelchair, where Hugh explains that he has passed something to her through intercourse—she will be pursued by an entity that only they can see, which can take the appearance of any person. It moves at a walking pace, but always knows where she is and will be approaching at all times. If it catches Jay, it will kill her and pursue the previous person to have passed it on. Hugh waits until a naked woman slowly approaches them to prove Jay is being followed, then urges her to have sex with someone else soon. He drives Jay home and flees. The next day, the police cannot find the naked woman or Hugh, who was living under a false identity. At school, Jay sees an old woman walking towards her, but no one else seems to notice; Jay flees the campus. Her sister Kelly and longtime friends Paul and Yara spend the night at Jay's house. Someone smashes a window; Paul investigates but sees no one. Jay then sees a disheveled, urinating, half-naked woman walking toward her and runs upstairs to the others, who cannot see the entity. When a tall man enters the bedroom, Jay flees the house by bike. With the help of their neighbor Greg, the group discovers Hugh's real name, Jeff Redmond, and find his home. Jeff explains that the entity began pursuing him after a one-night stand, and reiterates that the only option is to sleep with someone else, imploring Jay to do the same. He recommends that Jay drive to a distant location to buy herself time to think. Greg drives Jay, Kelly, Yara, and Paul to his family's lake house. The next day on the lakefront, the entity arrives in the form of Yara and attacks Jay from behind; the others cannot see it directly, but all except Greg (who has momentarily stepped away to urinate) see Jay's hair being grabbed by an invisible force and witness Paul being struck and flung across the beach. Jay shoots the entity with a pistol; it collapses but is only momentarily incapacitated. Jay flees in Greg's car and crashes, then wakes up in a hospital with a broken arm. To buy herself time, Jay has sex with Greg in the hospital. Greg denies the existence of the entity, despite the insistence of Jay's friends. Later, Jay sees the entity, in the form of Greg, walking towards Greg's house. It smashes a window and enters. Jay runs into the house and finds the entity, in the form of Greg's half-naked mother, attacking and killing him. Jay flees by car and spends the night outdoors. On a beach, Jay sees three young men on a boat. She partially undresses and walks into the water. Back home, Paul, willing to take the risk, asks Jay to pass it on to him, but she refuses. The group plans a last-ditch effort to kill the entity by luring it into a swimming pool and dropping electrical devices into the water. Jay waits in the pool until the entity arrives, appearing as her father. Instead of entering the pool, it throws the devices at her. Firing at an invisible target, Paul accidentally wounds Yara but shoots the entity twice before it falls into the pool. As it pulls Jay underwater, Paul shoots it again, and Jay escapes as it sinks to the bottom. When Paul asks if it is dead, Jay approaches the pool and silently watches as it fills with blood. Back at Jay's house, Jay and Paul have sex. Paul drives through town, passing sex workers. Yara recovers at a hospital. Later, Jay and Paul walk down the street holding hands, while a figure in the distance walks behind them.