Split

The curtain opens on Claire's birthday celebration, where pity invitee Casey is forced to endure the festivities alongside her reluctant host Claire (Haley Lu Richardson). As Casey's troubles with teachers are recounted by Claire's father (Neal Huff), it becomes clear that their acquaintance is born of necessity rather than choice. The girls' departure is disrupted when a mysterious stranger, Kevin (James McAvoy), inserts himself into their ride home, only to reveal his sinister intentions by rendering them unconscious.

As the toxin wears off, Casey begins to stir, her attempts to escape foiled by Kevin's hasty intervention. The scene shifts to a featureless room where Kevin has whisked the girls away, Marcia (Jessica Sula) being subjected to an unsettling ordeal that culminates in her desperate plea for solidarity. Claire, meanwhile, advocates for a united front against their captor, while Casey remains eerily calm, urging caution and prudence.

A flashback takes us back to a idyllic childhood scene where a 5-year-old Casey (Izzie Leigh Coffey) is taught the ways of hunting by her father (Sebastian Arcelus) and uncle John (Brad William Henke). Uncle John's whimsical account of a deer hunt serves as a poignant reminder of the innocence that has since been lost.

Meanwhile, Dr. Karen Fletcher (Betty Buckley), a therapist with a keen eye for detail, is captivated by news reports of the three missing girls, including Claire's father's frantic awakening to find his daughters and car vanished. An email from Barry, an enigmatic figure with a distinct Boston accent, piques her interest, leading her to meet with him in secret.

Little do they know, Barry is merely one of Kevin's multiple personalities, a sketch artist with a penchant for deception. As the threads of this complex narrative begin to entwine, it becomes clear that the truth behind the missing girls' disappearance lies at the intersection of trauma, psychological manipulation, and the blurred lines between reality and fantasy.

As the girls persist in their quest for liberation, they turn their attention to a minuscule crevice in the door, which reveals a seemingly benevolent woman engaged in conversation with their captor. Claire and Marcia appeal to this mysterious figure for aid, only to be shocked when the door creaks open and Kevin emerges, resplendent in a skirt and high heels, embodying his alter ego Patricia - a polite, British-accented persona. Patricia reassures the girls that their tormentor is cognizant of their presence and bound by rules prohibiting physical contact with them.

Meanwhile, Karen conducts a Skype conference, discussing her patients afflicted with dissociative identity disorder (DID), including Kevin. She elaborates on the unique characteristics exhibited by certain alters, noting that some possess capabilities not shared by others. Karen also alludes to her ability to sense which alter is currently in control, describing the phenomenon as "the light." Furthermore, she explains how individuals with DID can modify their bodily chemistry through mere thought.

The girls soon encounter another personality, Hedwig, whose mannerisms evoke those of a 9-year-old boy. Hedwig claims that Patricia and Dennis (Kevin's dominant persona) are displeased with him and that he is in trouble. Casey attempts to exploit this perceived rift by informing Hedwig that Patricia and Dennis remain angry with him, thereby exacerbating his predicament. As Hedwig departs, the girls redirect their attention to finding an exit through the walls. Claire discovers a hollow spot in the ceiling and begins dislodging plaster, while Marcia and Casey prepare to block the door should Hedwig return.

Just as Claire is poised to escape through the vents, Kevin reverts to his Dennis persona, prompting Claire to freeze in place. Casey and Marcia manage to hold back Hedwig's attempted entry long enough for Claire to make a break for freedom. However, her hasty ascent into the locker is short-lived, as her trembling breath betrays her presence to Dennis, who orders her to remove her shirt due to its supposed dirtiness. He subsequently locks her in a solitary confinement room.

In another online session with Karen, Kevin reappears as Barry, insisting that he has made significant progress. However, Karen remains skeptical, noting the peculiar characteristics exhibited by this alter - traits typically associated with other personalities like Dennis, indicative of obsessive-compulsive disorder (OCD). As their conversation progresses, Karen reveals her awareness of Kevin's 23 distinct identities, prompting Barry to reassert his claim that he has overcome his affliction. However, when Karen alludes to a 24th identity known as "The Beast," Dennis takes umbrage, insisting on the very real existence of this elusive persona.

Here is the rephrased section:

Patricia invites Casey and Marcia for a meal, but their evening takes an unexpected turn. As they enter the dining area, Marcia seizes the opportunity to reclaim her sense of freedom by stripping off her skirt, while Casey sheds her flannel shirt. Patricia, seemingly oblivious to the tension, busies herself preparing another sandwich, his precision and calmness only adding to the sense of unease. However, when he accidentally cuts the sandwich at an awkward angle, his frustration boils over, and he begins anew. Marcia, sensing a chance to strike back, seizes a chair and delivers a blow to Patricia's back before making a hasty retreat for help. Casey, attempting to follow suit, is caught by Patricia and ordered to return to her room. As the situation escalates, Marcia is eventually captured and locked away alone.

Meanwhile, Karen and her assistant Jai (M. Night Shyamalan) scrutinize security footage from outside the building, where a careless act of vandalism leaves a trail of trash in its wake. One couple navigates around the mess with ease, while Dennis walks directly through it, his deliberate stride catching Karen's attention as an intentional act.

In a lighter moment, Hedwig engages Casey in playful banter, asking to share a kiss, which she grants though it feels awkward. As they converse, Hedwig learns of his love for music and dance, citing Kanye West as a favorite artist. Casey invites him to show her his room and collection, where she discovers a peculiar window drawing - a closed window superimposed over an open one. As Hedwig's suspicions grow, she attempts to placate Casey, who pulls out a walkie-talkie and begins frantically calling for help while fending off Hedwig. She eventually subdues him, reclaiming the device.

In another flashback, Little Casey finds herself on a hunting trip with Uncle John, her father absent. As John's intentions become clear, Casey is forced to confront her own vulnerability. After a tense standoff, John manages to wrestle the rifle from her grasp, averting a potentially disastrous outcome.

As the story unfolds, Claire and Marcia concoct a plan to escape by manipulating the door lock from outside Marcia's room using a wire. However, their scheme ultimately proves unsuccessful.

As Karen (character not specified) steps into Kevin's abode, Dennis is awaiting her arrival, his warm hospitality masking an air of unease. He invites her in, and they continue their discourse about the enigmatic figure known as The Beast, which is comprised of several personas within Kevin: Dennis, Barry, Patricia, and Hedwig. Karen's trepidation gradually gives way to outright terror as she becomes increasingly entangled in the sinister undercurrents surrounding this mysterious individual. Before she can intervene on behalf of Claire, who is trapped in her room, Dennis pulls Karen away, leaving Claire to her fate.

Meanwhile, Casey stumbles upon a laptop containing video recordings of each of Kevin's personas. She watches Orwell, who delves into philosophical musings, and Jade, who struggles with diabetes. This glimpse into the psyche of the multifaceted Kevin Wendell Crumb (played by character not specified) serves as a precursor to the horrors that are to come.

As Dennis transforms into The Beast in an abandoned train car, his physical stature and strength become exponentially more formidable. Upon his return to his home, he finds Karen scribbling notes on a piece of paper. Her attempt to defend herself with a small knife is ultimately futile, as it shatters against the unyielding form of The Beast. In a gruesome display of brute force, The Beast squeezes Karen until her spine snaps, claiming her life.

Casey, now aware of the true nature of Kevin's personas, embarks on a desperate quest to locate the other girls. Her search yields the tragic discovery of Marcia's lifeless body, her stomach grotesquely torn open. Casey's subsequent encounter with Claire finds the young woman alive, but ultimately doomed as The Beast begins to feast upon her entrails.

As Casey confronts the aftermath of carnage, she stumbles upon the cryptic message Karen had written: "Say his name - Kevin Wendell Crumb." Her repeated invocations of this name, however, have an unexpected effect on The Beast, causing him to revert to his human form. A brief flashback reveals Kevin's childhood trauma, with his mother shouting his full name and chastising him for making a mess.

In the present, Casey is met with the grim reality that she has inadvertently revealed the extent of Kevin's crimes: Karen, Claire, and Marcia are all victims of his monstrous rampages. With a heavy heart, Casey confronts Kevin, who ultimately reveals the location of a gun within the cabinets. In a desperate bid to end the cycle of violence, Casey is forced to take matters into her own hands. As The Beast begins to reassert its dominance, Casey flees in terror, leaving Kevin's multiple personas to resume their deadly dance.

As Casey's desperate fingers grasp for shells to reload the gun, a eerie silence descends upon the dimly lit space as The Beast slithers across the ceiling, extinguishing the lights and plunging her into darkness. Undeterred, she finds solace in the confines of a nearby cage, loading the weapon with renewed determination. However, her resolute spirit is momentarily shattered when The Beast's ferocious attack leaves her shirt torn and leg scarred. Managing to escape his clutches, Casey retreats to the safety of the cage, only to find herself confronting the beast once more. This time, however, it's not aggression that fuels their encounter but a morbid curiosity as The Beast's piercing gaze falls upon the multitude of scars adorning Casey's body. A flash of her troubled past unfolds before our eyes - Little Casey, still reeling from the loss of her father, is consoled by John, who vows to become her guardian. The Beast's sudden epiphany that Casey is a soul untainted by darkness prompts it to spare her life and depart.

In the aftermath, a stranger stumbles upon Casey, and with gentle care, he escorts her outside to the safety of medical professionals. As she surveys the unfamiliar surroundings, Casey's gaze falls upon an enclosure teeming with wildlife, a poignant reminder of The Beast's own troubled past. Her rescue marks the beginning of a new chapter in her life.

Meanwhile, Kevin, now fully consumed by The Horde, remains isolated and controlled by its dominant personalities. Patricia reassures him that The Beast will protect them, a notion that seems both comforting and ominous. As the story concludes, a diner patrons gather to watch a news report detailing Kevin's heinous crimes. The anchorwoman's words are laced with intrigue as she mentions the uncanny parallels between The Beast's identity and the animals that inhabit the enclosure where it once worked. A patron's casual remark - "Mr. Glass" - serves as a haunting reminder of a similar case from 15 years prior, one that has left an indelible mark on our collective psyche.