In 1973, a young woman named Faith finds herself confined to a bed in the Mercy Home for Unwed Mothers as she goes into labor. The midwife, Rose Leeds, heartlessly hands Faith's newborn to her brother Talbot to bury alive, deceiving Faith by claiming her child has died. Despite Rose's lies, Faith hears the faint cries of her baby and desperately begs for the child's life, only to be met with cruelty when Rose injects her with poison. With her last breath, Faith curses Rose. Meanwhile, Talbot's sinister task is abruptly interrupted by an unseen force seemingly attacking him during the burial.
Fast forward to 2015, a musician named Liam Darrow takes his pregnant wife Rae Delatour, a crime reporter grappling with PTSD, to the now-transformed Mercy Home, known as The Mersey Inn, for her birthday celebration. The inn is run by Monica, Rose's daughter, who welcomes the couple as her only guests. As Rae begins to experience haunting visions of Faith and odd occurrences like a bloody door, Liam, dismissing her fears as symptoms of her mental illness, tries to keep things light-hearted.
One day, Rae goes on a nature walk and encounters Talbot, who warns her to avoid a barbed-wire section of the path. That night, Liam sets up his keyboard in a separate room, where he hears a ghostly child's voice. Monica later informs him about an antique ghost box that might connect him to the dead. As Rae shares her eerie experiences over dinner, Monica discloses the dark past of the inn, explaining its history as a sanctuary for unwed mothers, where the women were hidden from societal shame.
After a visit to a library reveals a grim history of child abuse and murders linked to the inn, Rae becomes increasingly determined to uncover the truth. Despite Liam's attempts to persuade her otherwise, Rae feels that her PTSD is somehow connected to the house's tragic past. As Rae digs deeper, she discovers a seemingly blank journal that reveals harrowing details about Rose’s actions, including the murder of minority babies.
The next day, Rae interviews police sergeant Grist about the inn's sinister history, learning shocking information about a report of a baby brutally killed. Talbot, compelled by guilt, later admits to Rae that he assisted Rose in her vile deeds and reveals her true identity—Faith's baby. This revelation only spurs Rae’s investigation further, leading to confrontations with Monica, who reveals her deeper connection to the dark history of the inn.
As Rae uncovers the truth, a series of horrific events unfold, including visions, strange encounters, and a confrontation that reveals Monica’s true nature. Under dire circumstances, Rae uncovers the chilling reality of the demon child and the sinister legacy that seeks to reclaim her.
On the final day of their stay, the supernatural escalates, culminating in a struggle for Rae's survival against the twisted ambitions of Monica, who is revealed to be an embodiment of Rose's malevolence. As the truth unfolds amidst betrayal, curses, and haunting memories, Rae's fight for her child and her own life becomes a desperate chase against time and supernatural forces.
In a shocking end, Rae wakes up only to find a coffin at her feet, bringing the nightmare back into focus as the demon baby rises.
