A young boy named Isaac is left grappling with grief following the untimely death of his father, James, in a tragic car accident. Isaac's stepmother, Laura, is also struggling to process the loss, and during a discussion about James' will, social worker Mary brings troubling news: if Laura does not claim legal guardianship, Isaac may be placed in foster care.
That night, as Laura watches sentimental home videos of James, she falls asleep only to be jolted awake by the pulsating blue lights of emergency vehicles outside their home. Mysteriously, she feels compelled to investigate and wanders into the woods, where she discovers a wrecked car and hears a haunting voice calling her name. Turning to face the source, she is confronted by a grotesquely disfigured apparition of James.
As the family copes with the aftermath of the funeral, the family pet, Bella, unnervingly reacts to a strange presence, chasing it off into the night, while Isaac finds solace in Laura's company, sleeping in her room. However, in the depths of the woods, an eerie creature takes on a human shape, eerily resembling James, and begins to call out to Isaac. The boy, desperate to hold on to his father, becomes convinced that his dad has somehow returned.
Isaac's belief intensifies when he discovers a wooden structure that mirrors one of James' architectural creations, prompting him to impulsively try to enter it. Laura, fearing for her stepson's emotional stability, expresses her growing concerns to family friend Robert, who offers to support them. Despite his intentions, Laura rebuffs his offer, troubled by Isaac’s increasingly erratic and violent behavior.
The tension escalates when Bella is found killed under mysterious circumstances, leading Laura to suspect Isaac may hold a darker secret. After a trip to the graveyard reveals that James' resting place has been vandalized, the presence of the creature in the house becomes undeniable. As Laura sets up surveillance to uncover the truth about Isaac's actions, the situation spirals further out of control. The creature’s influence becomes apparent when it urges Isaac to bring Robert to the same structure, resulting in a brutal confrontation.
The emotional turmoil reaches a breaking point when Laura confronts Isaac about his involvement in the chaos. She announces her decision to leave after realizing she cannot provide him with the support he needs. On a particularly harrowing night, Laura attempts to check on Isaac, only to witness the creature hovering over him, leading to a violent confrontation. In an act of desperation to protect her stepson, Laura stabs the creature, but it manages to escape, leaving both Isaac and Laura in a state of shock.
Years later, an older Isaac returns to the now-dilapidated structure, hoping to confront the lingering shadows of his childhood. Inside, he uncovers remnants of his past, including a photo of James that the creature once used to mimic him. The discovery of the creature's bones, devoid of a face, prompts Isaac to reckon with the impact of his traumatic childhood as he returns to find Laura, whom he now affectionately refers to as "mum".
