The film kicks off in 1988, right after the events of the third installment, where a supernatural entity brutally snaps Dennis backward, leading to his demise. Grandma Lois (Hallie Foote) then guides young Katie (Chloe Csengery) and Kristi (Jessica Tyler Brown) upstairs, introducing them to Kent (Don McManus), who they are told will be their teacher. Kent promises the girls that he is there to assist them with something that holds significance for their future.
Fast forward to 2013, we find ourselves in Santa Rosa, California, at the Fleege family home. Dad Ryan (Chris J. Murray) is seen spending time with his daughter Leila (Ivy George) as they await the arrival of Ryan's brother Mike (Dan Gill), who is hiding out after a difficult breakup. Ryan’s wife Emily (Brit Shaw) expresses her disapproval of Mike's extended stay. Adding to the mix is Skyler (Olivia Taylor Dudley), a family friend.
While rummaging through some belongings, Ryan and Mike discover an old camera along with a few tapes. Watching one tape reveals the girls as children, while Mike films the events, capturing moments with Katie and Kristi. Another disturbing tape features Kent pressuring Kristi to reveal what she sees, and Ryan is unnerved when Kristi describes Leila’s room. The unease escalates when Kristi responds affirmatively to Kent's query if she sees “him.” This interaction culminates in a chilling visual as a skeletal blue flash briefly overtakes Kristi's face, plunging the house into darkness.
As Christmas approaches, Mike records Leila adorning the tree with an angel. When Ryan captures the footage, he notices peculiar particles floating about, accompanied by underwater-like sounds as he moves past the camera.
Leila begins exhibiting alarming behavior. Ryan witnesses her with a bleeding hand pressed against the bathroom mirror, reciting something in reverse. They notice the handprint fading into the mirror just as a crack appears on its surface. Curious, Ryan and Skyler reverse the footage, revealing Leila chanting “Bloody Mary.”
Eager to explore further, Ryan sets up cameras in shared spaces and Leila’s bedroom. During Night #1, a dark figure emerges beside Leila as she slumbers, with Leila cheerfully conversing with it, referring to it as Toby. Ryan enters to find the entity vanishing at his presence.
As they delve deeper into the footage, Ryan and Mike invite Skyler to review the tapes with them. They notice the absence of any videos with Katie's and Kristi's mother and are intrigued by the quasi-cult dynamics portrayed in Kent's interactions and teachings.
During an outing with the camera, Mike and Skyler observe a ripple forming in the pool, leading them into the woods where they discover Leila alone. The lingering presence of Toby becomes increasingly conspicuous around her.
On Night #2, Ryan employs the camera to document the bizarre happenings. An entity unveils its grotesque, demonic visage as it flies toward Ryan, inducing terror. A deeper examination of the recordings reveals bizarre symbols drawn on the walls by Leila, prompting concern among the adults.
In subsequent nights, Leila’s alarming actions turn even darker, including incidents of gas being left on and the disturbing fall of the angel ornament. Frantic about Leila’s deteriorating behavior, Ryan and Emily enlist Father Todd (Michael Krawic) to intervene. His initial attempts to communicate with Leila take a dark turn when she suddenly lunges at him with supernatural strength.
As impending doom looms, Ryan and Emily make sense of Kristi’s chilling warnings captured in the tapes, revealing connections to a cult named The Midwives, whose sinister intentions revolve around using the blood of firstborns for their horrific rituals. The narrative thickens when they confront a crack in Leila’s room, leading to a tunnel she has mysteriously entered.
Night #6 reveals the culmination of their fears as Ryan and Emily, believing they’ve contained Toby, witness a bizarre twist when Skyler suffers a horrific fate at the hands of the very dark presence they’ve tried to expel. As chaos unfolds, Ryan meets a tragic end while Emily follows Leila into the depths of their horrifying revelations.
Emily’s frantic search leads her to the basement of Katie and Kristi's childhood home from 1992, where she encounters blood dripping ominously from the ceiling. Tension escalates when she meets the transformed entities of Katie and Kristi, beset by darkness, only to confront Toby, who has achieved a ghastly form.
In a heart-wrenching climax, Emily pleads for mercy, but instead faces her untimely demise. The unsettling narrative concludes with Leila grasping Toby's hand and disappearing off-screen, leaving audiences with an echo of dread as uncertainty looms over what was unleashed.
