Nicole Barlow is in the midst of making arrangements for her mother's funeral at their family home in San Pedro, California. Her sister, Annie, is hesitant to join, haunted by memories of their mother's harsh treatment. Attempting to reach out to her cousin, Liz, and her daughter, Eva, via video call, Nicole suddenly loses connection and becomes intrigued by a dark room that draws her attention with an open door.
Annie, alerted to Nicole's disappearance, arrives and discovers Nicole's phone along with a mysterious photograph. That night, plagued by unsettling dreams, Annie finds an eerie photo featuring two pregnant women—her mother alongside a woman in a floral dress. At the funeral, discrepancies arise as it's revealed that Annie possesses one blue eye and one green, a trait absent in their mother.
Following the funeral, Annie connects with Liz and Eva, and together they retreat to their mother's house. However, visions haunt Annie as she dreams of a shirtless man in tears, and her phone reveals a mapped location. When she wakes, a shadowy figure in the hallway drives her to check on Liz, only to find her bed empty. In a terrifying encounter, an unseen force menaces Annie, prompting her and Eva to flee the house.
The police, including Officer Bill Creek, dismiss Annie's claims of supernatural hauntings, insinuating her possible involvement in the mysterious disappearances. While staying in a motel, Annie becomes fixated on the address displayed on her phone and discovers a blurry image of a figure clad in a floral dress. That night, her nightmares escalate as she witnesses both the sorrowful man and the decapitated woman.
In the morning, fraught with anxiety, Annie revisits their family home with Bill Creek, where they uncover a concealed room that Annie cannot remember. Feeling isolated, Annie enlists the help of her psychic friend, Stevie, and her brother, Giles. Upon entering the hidden room, Stevie experiences a severe episode and repetitively utters the name "Judas." The group is then confronted by the spectral form of a woman in a floral dress, leading Annie to the chilling realization that her mother's spirit is not the one haunting the house.
Outside, a confrontation with Giles erupts over the dangers Annie has placed everyone in, resulting in an angry departure with Stevie. Alone, Annie conducts her research on "Judas," a serial killer linked to a gruesome murder involving a victim in a floral dress, Jennifer Glick, who turns out to be related to her mother.
Officer Creek's investigation into the house leads him to another secret room, but tragedy strikes when he meets an untimely fate at the hands of an unseen attacker. In desperation, Annie resorts to a makeshift Ouija board, aiming to connect with Glick, who validates that her murder was at the hands of the "Judas Killer," her uncle.
As dread deepens, Annie encounters Judas emerging from a hidden hatch. She stumbles upon the lifeless bodies of Creek and Nicole, and in the throes of horror, she takes Creek's gun but is quickly overpowered by Judas. Awakening in captivity within a closet, she plots her daring escape, stabbing Judas with a coat hanger.
In a final confrontation, Glick's spirit intervenes, guiding Annie back to Creek's gun. In a climactic moment, she shoots Judas, noting his heterochromia, mirroring her own. Following the chaos, Annie gains custody of Eva, but with Liz and Nicole gone, their house is sold and under renovation. In the chilling closing scene, as Annie sleeps, a sense of unease prevails as Judas' eye flickers open within her dreams, hinting that their harrowing saga may not yet be over.
