As the clock ticks down, Hazel, her boyfriend Ade (Tom), and their partners-in-crime, Mark and James, devise a daring plot to kidnap Katherine, a diamond heiress, within a tight six-week timeline. Despite Mark's hesitations about the rush, he ultimately succumbs to the pressure from Hazel and Ade, who are motivated by Ade's looming trial for the tragic accidental death of his brother George. With everything on the line, Mark reluctantly joins the risky mission.
Fast forward six weeks, the team stealthily breaks into Katherine's luxurious estate, only to find it mysteriously deserted, the alarm system already disabled. They manage to capture Katherine and take her to a secret hideout in an abandoned warehouse. However, they are taken aback by her disheveled and fragile state, but they persist in their ransom plan.
Katherine initially resists, ominously warning them that letting her go will only lead to severe consequences. Eventually, Hazel's persuasiveness wins out; Katherine agrees to record a ransom video in hopes of a swift resolution. Yet, the group soon realizes that reaching out to her parents is impossible. Frustrated and desperate, Hazel sends Ade and James to investigate Katherine's home.
Their return reveals a disturbing situation: the estate is filled with the stench of rotten food, and decay permeates the air. James stumbles upon a horrifying sight in the cellar, discovering the grotesque remains of two mutilated priests. Ade's eyes widen in horror as he pieces together that Katherine's parents have been gruesomely murdered, their anguished spirits seemingly haunting the residence.
Tormented by visions from their own troubled pasts, Mark and his crew flee the property, leaving behind the chilling videotapes they uncovered. As they escape, Ade swerves to avoid the ghostly apparition of George, while James is overwhelmed by spectral images of his mother, causing them to lose their grasp on reality as guilt and dark forces close in around them.
In the ominous darkness of the warehouse, Hazel and Mark face the relentless hauntings from their pasts. The ghostly figures of their loved ones—Hazel's mother serving as a personal specter and Mark's deceased daughter, Sarah—remind them that the horrors they've stumbled upon are unnervingly real. Meanwhile, James’ condition worsens, forcing his companions to abandon him as they delve deeper into the haunting mysteries on the videotapes. The first tape, a gift from Katherine, recounts the sinister history of her ominous home and its dreadful legacy, including the unsettling fate of Hazel's mother—information she had kept hidden from her companions. As they watch on, their unease grows, leading to even darker revelations about the supernatural activity plaguing the house.
The next tape reveals an even more chilling truth: a priest discusses a malevolent entity that thrives on grief, one that has taken control of Katherine. This dark spirit has claimed the house as its playground, hidden far from a sacred relic protected by the Vatican. As panic escalates, they recognize that Katherine's increasing power is a dire threat to them all.
Confronted by the increasingly demonic Katherine, Hazel (Hazel), Ade, and Mark must face her sinister designs: with two more victims required, she can finally escape her hellish binds. Meanwhile, James succumbs to the influence of his mother’s spirit, seeking to infect his friends with despair. In a desperate attempt to save himself, Katherine tempts Mark with the chance to reunite with Sarah, urging him to betray Hazel and Ade. Consumed by temptation, Mark releases Katherine, effectively delivering his friends into her sinister ambitions.
As chaos ensues, James becomes a threat, possessed by his mother's ghostly presence, while Mark fully surrenders to possession. In a moment of sacrificial bravery, he buys time for the others to escape, leaving them to face profound despair. Overwhelmed by guilt, Ade tries to speak to George's spirit but ultimately decides to end his life rather than risk being the final sacrifice for the demon.
In a bid for survival, Hazel finds guidance from her mother's spirit, which leads her toward freedom. The possessed Katherine, along with Mark and James, pursuit her relentlessly. As they nearly corner her by Ade's wrecked van, Hazel fights back, reclaiming a lighter from the debris to ensnare Katherine in the chains that once bound her. While Katherine struggles to escape, Hazel’s mother appears, striking down Mark and James with vengeful fury.
Recalling the priests’ earlier attempts to destroy Katherine, Hazel seizes the opportunity, incapacitating her and dousing her in gasoline before igniting the van into a raging inferno. As she escapes the blazing destruction with sirens approaching, Hazel leaves behind a path of devastation, forever marked by the horrors that she has endured.
