As John James navigates the challenges of his new life in rural South Carolina alongside his teenage daughter Louisa and young son Sam, the emotional strain of their fractured family dynamics becomes increasingly evident. Tensions run high, particularly between John and Louisa, who accuses him of never truly loving her mother and blaming him for the aftermath of their family's turmoil. Their move into an old house, steeped in its own secrets and stories, adds to the mounting unease that envelops them.
On the very first night in their new home, Louisa's sensitivity to her environment heightens as she perceives strange noises coming from outside her bedroom window. In the darkness, an enigmatic figure lurks above, unknown to her. The following day, while exploring the vast fields and dense forests around their home, the children come across a mysterious mound that fascinates Louisa but unsettles Sam.
As John digs deeper into the history of their residence, he stumbles upon a chilling legend surrounding it – the ominous disappearance of a previous resident, a woman whose fate remains shrouded in mystery. This unsettling discovery coincides with the grotesque find of their pet cat’s mutilated remains near the house, hinting at sinister forces lurking nearby.
As the days pass, Louisa’s growing obsession with the mound becomes apparent, leading to a troubling change in her demeanor. One sunny afternoon, she is startled by the strange noises she had previously heard, a harbinger of John's own disturbing experience as he injures his hand while washing dishes. That same night, John uncovers muddy footprints that lead from the unlatched bathroom door, where he finds Louisa sitting in the tub, her body covered in dirt. As the shower rinses away the mud, the water ominously turns crimson, suggesting something dark lies beneath the surface. Later, John encounters Louisa in a spellbinding sleepwalking state, only to discover a disturbing straw doll containing a live spider hidden in her room.
The next morning, Louisa surprises John by emerging from her room dressed in a short black dress and wearing makeup, raising suspicions about her nighttime escapades. When he confronts her about the unsettling doll, she feigns ignorance, leaving John haunted by unanswered questions. As darker forces close in around them, the James family must confront the supernatural entities threatening to unravel their lives.
At school, Louisa contends with a haughty classmate, whose barbs cut like a knife. Back home, John discovers a heap of muddy laundry in Louisa’s bedroom, a sinister reminder of the chaos brewing just beneath the surface. Driven by an unshakable curiosity, John ventures outside and is horrified to uncover the severed head of Louisa’s beloved doll alongside the gruesome remains of a blood-stained blackbird. Shortly after, a phone call from Louisa's school brings more troubling news: she has fallen ill and requires his attention in the infirmary.
While tending to his daughter, John notices the same snide classmate, bandaged from an apparent accident on the stairs. Later, Louisa's teacher, Cassandra, offers John a sympathetic ear regarding their shared concerns for Louisa's well-being, but this fragile sense of camaraderie quickly dissolves when John discovers a nest of spiders residing in the kitchen drawer where the doll lay; its grim presence now brimming with malice.
That night, John’s gaze catches Louisa emerging from the shadowy woods, her silhouette illuminated by the moonlight. The scars on her neck signal the emergence of an unsettling truth. Despite his worries, Louisa remains evasive, disappearing into the darkness. At dinner, she devours her meal with an insatiable hunger, as if compelled by an unknown force.
John's growing anxiety leads him back to Cassandra’s understanding disposition, yet Louisa soon begins hearing strange noises outside, compelling her to investigate. Returning home, John sees a shadowy figure resembling Louisa darting through the trees. The chilling sounds of growling and breaking twigs urge him to flee in terror.
When day breaks, John's agent pays a visit, providing a momentary distraction from the encroaching dread. However, when Sam is sent to the attic in search of a book, he falls victim to the same haunting sounds that have plagued the family, his screams reverberating through the halls. This leads to an intense confrontation as John chastises Louisa for her apparent apathy towards her brother, while she remains eerily unaffected.
As shadows deepen around them, John takes to the internet, searching for clarity about the burial mounds that seem to be at the heart of their misfortune. His investigation yields an article that he shares with Professor White, but he is met with an aloof dismissal. Undeterred, John continues digging, peeling back layers of dark history involving Sarah Wayne, the home’s former occupant, and her daughter Emily, whose own disappearance mirrors the ominous events now entangling John's family.
With the urgency mounting, John sets out to confront Roger Wayne about Emily's enigmatic fate. Louisa, eyeing John's departure, fixes her gaze on him from the window, the ominous scars on her neck hinting at the horrifying events soon to unfold. As John arrives at Roger's vacant home, dread envelops him, leading him deeper within the property to discover a peculiar nest woven from twigs and straw in the girl's room. The walls are adorned with a haunting illustration of the burial mound, ominously captioned “home” – a word that takes on new, chilling meaning amid Roger's shocking revelation that Emily lost her life in a fire at the house he had set ablaze. His unsettling assertion that Emily is no longer his granddaughter, consumed by a dark force, sends chills down John's spine.
As John navigates this surreal and eerie reality, Mrs. Amworth, the unsuspecting babysitter, finds herself locked out of the house, besieged by primal growls echoing nearby. Sam, sensing the encroaching menace, retreats to safety while Mrs. Amworth’s desperate pleas go unanswered. Upon John's return, chaos reigns as he discovers Louisa engulfed in terror, her eyes swollen from weeping.
Haunted by dreams of swirling darkness, John becomes increasingly aware of Louisa’s transformation as she eerily states, > “I’m your new daughter.” The morning reveals a similar nest hidden in Louisa’s closet, deepening John’s concerns. When the Professor White arrives with chilling updates about an ancient civilization that revered the burial mounds as sacred homes for their deities known as “mound-walkers,” John’s reality begins to shatter further. This shift claims an even darker tone as the professor reveals the monstrous ritual surrounding the mounds and the sinister gifts exchanged.
Desperate to halt the unfolding horror, John orders a bulldozer to destroy the mound, only to unearth the grotesque remains of Mrs. Amworth buried within. Meanwhile, Louisa demonstrates an unsettling prowess, digging into the schoolyard with newfound intensity, drawing hidden energies from the earth. As John is taken away for questioning at the police station, Cassandra takes the reins with the children, veiling the ominous secrets that bubble beneath their surface.
As Officer Ed Lowry drives John home that fateful night, a vicious attack unfolds, leaving Lowry at the mercy of primal forces lurking within the shadows. Upon John's arrival, a scene of disarray awaits, capped by the shocking discovery of Cassandra's lifeless body, a sight that drapes the atmosphere in horrific anticipation. Louisa stands silently in the doorway, her presence with an eerie calm amidst the chaos.
John’s attempts to rally the children and escape are met with Louisa’s dogged refusal to leave, plunging the house into turmoil as Mound-walkers unleash their fury upon them. After dispatching three of the creatures, John frantically searches for Louisa, only to find her missing. Her terrified screams drag him into the maw of the mound, compelling him to act.
Braving the unknown, John desperately lights a flare and crawls into the shadowy tunnel, trusting that Sam will navigate the uncertain fate awaiting him. After locating Louisa unconscious and caked in mud, John realizes her transformation into one of the monstrous beings is beginning. As a last-ditch effort to escape, he blocks the tunnel entrance with the leaking fuel canister, partnering his doubts with fleeting hope. Louisa collapses, pleading with him not to abandon her as she fights against her monstrous change.
All around, chaos erupts with the mound ignited, and John makes a final stand against the creatures, even if it means making the ultimate sacrifice to guarantee his daughter’s safety. As the inferno engulfs the shadowy landscape, Sam stands paralyzed by terror, clutching a family portrait that serves as a reminder of their humanity in this nightmare.
As the screen fades to black, an indistinct figure emerges from the flames, cloaked in mystery. The chilling growls of the creatures resonate through the woods and house surrounding Sam, departing him with a haunting, lingering question: “Daddy?”
