It has been three weeks since the notorious crime spree orchestrated by Kevin Wendell Crumb, known as "The Horde," played by James McAvoy. Kevin, a former employee of the Philadelphia Zoo, possesses 23 distinct personalities, each influencing his behavior and physical capabilities. Among these personalities are Jade, a teenage girl, Barry, an elegant man, and Patricia, a refined British woman. However, when provoked, they transform into the fearsome "The Beast," a superhuman with extraordinary agility, strength, and a cannibalistic nature.
Enter David Dunn (Bruce Willis), a vigilante superhero who, alongside his now-adult son Joseph (Spencer Treat Clark), takes on the mantle of "The Overseer." They aim to rescue four cheerleaders abducted by Kevin, whose dangerous impulses threaten their very lives. Using his unique extrasensory gift that allows him to perceive crimes through touch, David tracks down the cheerleaders but faces off against Kevin's predatory alter ego, "The Beast."
In a dramatic confrontation, their struggle spills into the streets, drawing the attention of a specialized faction of the Philadelphia Police, led by Dr. Ellie Staple (Sarah Paulson). As a psychiatrist specializing in delusions of grandeur, she aims to convince David and Kevin that they are simply deluded about their supposed superhuman capabilities. She employs a machine designed to manipulate Kevin's personalities, commanding him to relinquish control of "The Beast."
Both David and Kevin find themselves incarcerated in a mental institution for the criminally insane, where they encounter Elijah Price (Samuel L. Jackson), also known as "Mr. Glass." Elijah is a brilliant yet twisted mastermind who aims to prove the existence of superhumans like David and Kevin. In their attempts to manipulate the patients into accepting their normality, Dr. Staple is determined to undermine their beliefs, knowing David's only apparent weakness is water and that she has mechanisms in place to maintain control.
Through various visits from loved ones, including Mrs. Price (Charlayne Woodard) and Casey Cooke (Anya Taylor-Joy), who survived her encounter with “The Beast,” the patients begin to question their convictions. Dr. Staple intensifies her psychological warfare, revealing Elijah's MRI results that suggest an unusual brain structure fueling his obsession with superhumans.
As tensions escalate, Elijah pretends to remain subdued, secretly plotting their escape. He ultimately stirs the "Beast" to awaken just in time for a public showdown at the unveiling of Philadelphia’s tallest tower, aiming to expose superhumans' existence to the world. With a desperate fight against David looming, Elijah uses his cunning to reveal David's vulnerability to water, throwing everything into chaos.
Despite their struggles, revelations about familial tragedies and manipulations surface, leading to a climactic confrontation between the three superhumans. While David is on the brink of death, and the "Beast" confronts the consequences of his dual existence, Casey’s desperate plea to Kevin brings forth his true self, resulting in devastating outcomes for all involved.
In a shocking turn of events, Dr. Staple resorts to extreme measures to erase all evidence of their existence, drowning David in a flooded pothole, while Elijah and Kevin meet tragic ends. However, death proves not to be the conclusion, as unbeknownst to Staple, Elijah had previously orchestrated a live stream of their harrowing tale. With the truth finally revealed, the legacy of superhumans is set to unfold in the public eye as Joseph, Casey, and Mrs. Price choose to disseminate this vital information, forever altering the narrative of their existence.
