Amityville Christmas begins with the Hendricks family—Robert, Mary, their teenage children Sarah and Michael, and toddlers Noah and Lily—arriving at the infamous Amityville house just before Christmas. Robert, an academic obsessed with proving the existence of the supernatural, is determined to document paranormal phenomena for his book. Mary, deeply apprehensive, grows concerned for her children’s safety, while Sarah is rebellious and dismissive of the house’s haunted reputation. Michael, quiet and distant, seems captivated by the house.
Strange occurrences begin immediately. Cold drafts, flickering lights, and eerie whispers unsettle the family, but Robert is excited by the potential to capture proof of the supernatural. He sets up cameras throughout the house, oblivious to Mary’s growing fears. The first major incident occurs in Noah and Lily’s bedroom, where they are overwhelmed by the smell of fecal matter, swarms of flies, and crayon drawings of demonic faces appearing on the walls. The terrified children scream for help, but Robert is thrilled by what he sees as undeniable evidence of paranormal activity.
As the days progress, Michael’s behavior grows darker. He develops a disturbing attraction to Sarah, which leads to two unsettling sexual encounters. The first begins seductively but becomes rough, causing Sarah to retreat to her room, confused and frightened. In the second, Michael, now under the influence of the house, seduces Sarah again and forces her to curse God while they have sex. This scene marks Michael’s full surrender to the house’s evil influence.
During Christmas dinner, the turkey they are carving suddenly comes to life, twitching violently. Chaos erupts as the family reacts in horror to the grotesque scene. This bizarre event heightens tensions, leading to a final argument between Robert and Mary. Traumatized by the escalating horror, Mary decides to leave the house with the children, but Robert, still obsessed, refuses to leave.
After this argument, Michael, fully possessed by the house’s dark forces, strangles Robert to death. His murder of his father marks his complete descent into madness, fully controlled by the house’s evil. Mary, devastated and terrified, attempts to protect her remaining children, but it’s too late.
Michael’s violence intensifies when he attacks Mary, fully submitting to the malevolent forces controlling him. Sarah tries to intervene, but Michael brutally kills her with a fire poker, smashing her head in as Mary watches in horror.
Pastor David, a family friend, arrives at the house sensing something is terribly wrong. Inside, he discovers Robert crucified to the wall with Christmas lights and Sarah’s body, her head crushed. As he searches further, he finds the dead bodies of Noah and Lily, confirming the extent of the house’s evil.
Determined to stop the madness, Pastor David moves upstairs to the master bedroom, where he finds Michael raping Mary, who is in a trance-like state. A spiritual confrontation ensues as Pastor David attempts to exorcise the demon possessing Michael. However, the evil within Michael proves too strong, and Michael kills Pastor David by snapping his neck.
The film concludes with Michael standing victorious, fully possessed by the house’s evil. Snow falls outside, creating an eerie contrast to the horror inside. Michael gazes out through the iconic Amityville windows, his eyes glowing with a demonic light. The curse of the Amityville house remains unbroken, having claimed another family.