Laura Hall, portrayed by Alicia Silverstone, finds herself in a heartbreaking situation after she separates from her novelist husband, Richard Armitage. Amidst the turmoil, Laura takes her own life upon learning that Richard plans to marry Grace Marshall, played by Riley Keough, a woman intertwined with a dark past involving a fundamentalist Christian cult. Grace, who emerged as the singular survivor of a mass suicide led by her father, Aaron, struggles with the weight of her tragic history.
In the wake of their mother’s death, Richard and Laura’s children, teenage Aidan, portrayed by Jaeden Lieberher, and young Mia, played by Lia McHugh, are consumed by grief. Six months after the tragedy, Richard announces during Thanksgiving that they will spend Christmas together with Grace at their secluded lodge in rural western Massachusetts. This decision is met with hostility, as Aidan and Mia grapple with their feelings toward Grace, who embodies both their father’s new beginning and the shadow of their mother’s demise.
When the family arrives at the lodge, the pervasive Catholic symbols evoke painful memories for Grace, leading to a growing sense of dread. On one tense night, a moment of comfort arises when Aidan prepares cocoa for Grace and Mia during a movie blur. However, this fragile peace shatters when Grace wakes to find that everything familiar has vanished—her belongings, the food she prepared, even her dog. Confusion reigns as the clocks ominously display January 9th, harboring the revelation of a nightmare: Aidan reveals a terrifying dream of their suffocation due to a gas heater malfunction, solidifying their belief that they may be trapped in the afterlife.
As the days stretch on, Grace, hindered by anxiety and the withdrawal from her medication, begins to sleepwalk and experience vivid hallucinations tied to her father’s haunting sermons. In a desperate move, she tries to reach the nearest town but only gets lost over and over, encountering remnants of her past. During a haunting journey, she discovers a chilling photo of Aidan and Mia, alongside harrowing evidence suggesting they may have succumbed to a tragic fate themselves.
Aidan’s increasing hysteria leads to a misguided attempt at proof of their demise when he hangs himself in the attic, only to survive. The situation escalates further as Grace’s mind unravels, culminating in a stark confrontation with her dog’s lifeless body. Ultimately, the truth surfaces as Aidan and Mia confess their elaborate deception to torment Grace. They orchestrate a series of gaslighting schemes to manipulate her sanity, hiding their devices while the aura of their father’s presence lingers, unknowingly leading her to a state of total breakdown.
As the children attempt to escape the wrath of their delusional stepmother, they are met with her desperate and violent actions, culminating in a tragic confrontation with Richard’s return. In a chilling climax, Grace’s belief in their purgatorial fate drives her to commit a horrific act against Richard, leaving Aidan and Mia at her mercy. Isolated and terrified, they find themselves forced to navigate a desolate hell, with Grace now fully consumed by her convictions and placing her twisted faith above all else.
