As the eerie tale unravels through the perspective of 9-year-old Louis Drax, we delve into a sequence of seemingly unrelated incidents that culminate in a chilling climax. Flashbacks highlight Louis's sessions with psychiatrist Dr. Perez (/actor/aaron-paul), where he recounts a series of near-fatal accidents, including the most recent incident where he tumbled off a cliff. But cracks begin to form when Dr. Perez shares Louis's concerns with his mother, Natalie (/actor/sarah-gadon), leading her to abruptly terminate the therapy sessions.
In the present, medical professionals label Louis as dead after his latest mishap, but in a surprising twist, he stirs awake in the morgue, only to be found in a coma-induced haze in the intensive care unit. His father, Peter (/actor/jamie-dornan), has mysteriously disappeared, casting suspicion on him as the prime suspect for attempted murder.
Dr. Allan Pascal (/actor/aiden-longworth), an adept physician, steps up to care for Louis, but his involvement complicates as he grows closer to Natalie, much to Peter's chagrin. Amidst a simmering attraction, they share whispered secrets during moonlit strolls. However, their budding romance is disrupted by threatening letters from an unidentified sender, who claims to be Louis himself.
As the investigation into Louis's condition spirals into darker territories, Detective Dalton uncovers startling information: Peter may not be Louis's biological father, and Natalie once contemplated giving Louis up for adoption. This revelation fractures Natalie, prompting her to confess the difficult truth surrounding Louis's birth to Allan.
With stakes escalating, Violet, Louis's grandmother, arrives at his bedside, sensing the developing romance between Natalie and Allan. She cautions Allan about Natalie's tumultuous past, painting a vivid picture of a woman who may be prone to manipulation. Just when equilibrium seems achievable, Dalton bursts in with shattering news: Peter's body has been found at the bottom of a cliff, having met his demise several days before.
Throughout this labyrinthine narrative, Louis serves as our guide through a twisted world, haunted by a mysterious creature wrapped in seaweed—symbolic of his troubled psyche. In a surreal climax, we discover that this figure embodies Louis's father, Peter, whose lifeless body was discovered entangled in seaweed in a cave.
As Allan stirs awake from a nap, another doctor informs him of a strange episode: during his sleep, he not only sleepwalked but also scribbled a prescription for Natalie, calling for dangerously high doses of insulin and chloroform. This unsettling revelation, along with the anonymous messages and Allan's recurring dreams, leads him to consider that Louis has been manipulating his actions while he sleeps. With this suspicion gnawing at him, Allan confides in Dr. Perez, who promptly connects Allan to an electrocardiogram, enabling direct communication with Louis through Allan's mind and voice.
In this unconventional exchange, Louis recounts the events of their fateful picnic. During the outing, Natalie attempted to coerce Louis into eating candy while denying it to Peter, resulting in a confrontation that spiraled into chaos. In the heat of the moment, Natalie pushed Peter off the cliff, sealing his fate. Overcome with grief, Louis was driven to the cliff's edge, where he was drawn back into another violent clash with Natalie and Peter before purportedly taking his own life by jumping.
However, just as despair appears insurmountable, Louis's heartbeat falters, prompting Allan to spring into action. As he desperately revives Louis using a defibrillator, it becomes shockingly clear that Natalie had orchestrated Louis's so-called "accidents"—a series of sinister events that included poisoning his candy, electrocution, and even smothering him with a pillow. With Allan successfully reviving Louis, Natalie's malevolent intentions are laid bare.
As time flows, Allan separates from his wife before visiting Natalie, who is now confined to a psychiatric ward under Dr. Perez's care. The doctor reveals that he has diagnosed Natalie with Munchausen syndrome by proxy, a disorder characterized by pretending to have illnesses in another person, typically one’s child. As Allan absorbs this dark truth, it dawns on him that Natalie is pregnant, her baby likely sired by him.
In a deeply poignant moment, Louis remains in a comatose state, contemplating the bittersweet possibility of staying asleep forever—an escape that would allow him to remain with his father. Just then, Peter's ethereal voice urges Louis to awaken and embrace life, illuminating the beauty and wonder that the world offers. Thus, with a flicker of hope, Louis ultimately emerges from his coma, bringing the film to a heartfelt conclusion.
