Kevin, a young man with dissociative identity disorder, harbors 23 distinct personalities within him, each with its own perspective on the world and agenda. When he kidnaps three teenagers—Casey, Claire, and Marcia—the girls find themselves trapped in a dark and mysterious place, where each of Kevin's identities manifests in terrifying ways. As the girls try to escape, they must confront not only the cage they are locked in but also Kevin's personalities, which range from an innocent child to a monstrous manipulator called "The Beast."
Casey, who has a complicated past and has learned to survive through cunning and perseverance, becomes the key to understanding Kevin and his personalities. As the young women struggle to find a way out, the story reveals the traumas that have led Kevin to develop his complex psyche. The relationship between Casey and Kevin's various personalities deepens, adding a layer of emotional tension to an already unsettling plot.
With a surprising twist at the end, the film is not only a disturbing psychological thriller but also explores themes of trauma, identity, and the struggle for acceptance. The direction by M. Night Shyamalan and James McAvoy's masterful performance create a unique and unsettling cinematic experience that leaves the viewer questioning the nature of the human mind.