After a family moves into the Heelshire Mansion, their young son soon makes friends with a life-like doll called Brahms.
After a home invasion, mother and son Liza and Jude are left traumatized, with Jude remaining silent for five months. With husband and father Sean, they move to the Heelshires estate where Jude finds and befriends the Brahms doll.
Jude’s behavior gets worse around Brahms, with many weird things happening in its presence. After learning the dark history behind the home and the doll, Liza and Sean try to help Jude. He is kept in a trance by Brahms, nearly killing Liza before Sean smashes Brahms’s head, revealing a demon inside, but Jude throws it into the fireplace.
The family moves back home, but Jude keeps a mask of Brahms and still seems to have his spirit lingering.
A home invasion leaves Liza with a head injury and her son Jude traumatized and silent for months. Along with Sean, Liza’s husband and Jude’s father, they move across country to the Heelshires’ property. While exploring the woods, Jude finds a porcelain doll buried in a shallow grave in the ground and dusts off the dirt before deciding to take him home. Liza and Sean believe he is using the doll to express his feelings but it becomes more sinister with the doll laying down his rules. Jude becomes withdrawn in his room, carrying the doll with him wherever he goes.
The parents soon learn the evil history of the doll, with all the killings and suicides. More unusual incidents happen, like the dining room table collapsing when Jude warns his mother not to make the doll angry. Liza also sees horrific and violent drawings in Jude’s notepad. Jude’s Uncle Liam, Aunt Mary, cousins Will and Sophie visit. Jude, Will and Sophie go play outside and something happens to one of the children. Groundskeeper Joseph enters the house, aiming a shotgun at Liza. He begins telling the story of how Brahms asked him to put him back together, making Jude an easy target for the doll as he was not strong-willed. He then tells her that Brahms will take Jude away forever. Liza attacks Joseph with the shotgun, before beginning to search for her son. She goes into the basement and finds Jude in a trance-like state, ready to sacrifice himself with the doll. Liza manages to convince Jude that they will take Brahms home and become a family, without seeing Sean come in and break Brahms’ head with a croquet mallet before Joseph comes running in. Brahms’ head shatters, revealing a demonic doll underneath, more sinister than the porcelain innocent face. Brahms then kills Joseph without hesitation.
Jude picks Brahms up, convincing him they will be fine before tossing the doll into the fire. The family embrace and return to their home, living happily as before the home invasion incident. At night, Jude puts on his Brahms face mask.
The film starts with Liza (Katie Holmes) coming home where her son Jude (Christopher Convery) plays a prank to scare her. They then call Jude’s dad/Liza’s husband Sean (Owain Yeoman) through a video chat, as he is working late again. Liza later tucks Jude in, but hears noises in the house and goes to investigate. She is then attacked and knocked unconscious by a burglar, and Jude is left helpless.
Five months later, Jude is left traumatized from the incident and has remained silent since then. He meets frequently with a therapist, Dr. Lawrence (Anjali Jay). Liza has also suffered a head injury and is equally traumatized, having nightmares about the attack. Sean and Jude see this and they know they need to get away.
The family moves to the Heelshire estate to stay in the guest house for the time being. After checking out the house, the family goes for a walk outside near the woods. Jude wanders off and comes across the Brahms doll buried in the dirt. Liza and Sean run to find him and see Jude with Brahms. The boy also finds a list of rules for Brahms before Liza helps him clean the doll up. Afterward, Liza appears to see Brahms turn his head to look at her, only for him to be normal when she looks back. Of course, he turns his head for real when she steps out.
Jude carries Brahms with him everywhere throughout the day. When he goes back outside, he and Liza are startled by a German shepherd dog called Oz, before his owner, groundskeeper Joseph (Ralph Ineson) comes by. He introduces himself to everyone once Sean comes by, but he looks spooked upon seeing Jude holding Brahms. Later, Liza and Sean discuss how much attention Jude is giving Brahms, which Sean thinks is just Liza diverting from her own trauma from the burglary. The two go to check on Jude and hear him reading out loud to Brahms, which excites them since he is talking again. However, he stops once they enter his room.
Liza later has a nightmare that she is attacked in her home again before seeing Jude wearing a mask of Brahms’s face.
The next day, Jude continues to be mute but has also written up a list of more rules for Brahms. He also starts acting bratty around his parents as an apparent result of Brahms’s influence. Liza remains creeped out by Brahms and observes weird things happening around the house when he is near, like the TV turning on by itself. Liza and Sean contact Dr. Lawrence, who thinks that maybe having Brahms around is good for Jude to readjust. While Jude is outside with Brahms, Joseph comes up and talks to him while Liza looks up the history of the house. She also tries to learn more about the doll itself by inspecting the serial number under Brahms’s foot. Liza also finds a notepad with disturbing drawings of Brahms and what appear to be conversations between Jude and Brahms, indicating that Brahms wants to murder Sean and Liza.
While having dinner, Jude dresses exactly like Brahms and doesn’t eat. After reprimanding him, Liza washes dishes when she hears the dining room table collapse. Jude runs off and hides in another room before his parents go find him, whereupon he vocally apologizes, and his parents are happy to hear him talk again. They are later visited by Joseph, who went off looking for Oz and found him dead in the woods. He tells Sean and Liza about the previous couple living in the house that committed suicide.
The family is visited by Sean’s brother Liam (Oliver Rice) plus his wife Mary (Joely Collins) and kids Sophie (Daphne Hoskins) and Will. The kids go outside to play, but Will taunts Jude for having Brahms, as well as calling him “mental” and mocking the home invasion incident. Jude warns Will not to make Brahms angry. The two then have a tug-of-war over something Will takes, which leads to him stumbling backward and getting impaled through the shoulder by a sharp piece of wood lodged into the ground. He’s rushed to the hospital, but it’s implied Brahms had something to do with this.
Later that night, Liza reads up more on Brahms, learning about the dark history of the real Brahms and the atrocities he committed. Meanwhile, Sean learns from another guy downtown about the mansion’s history. Liza goes to look for Jude but finds Joseph entering with a shotgun. He tells Liza that he put Brahms back together because he called to him, and he knew that Jude would be an easy target for Brahms to get ahold of. Liza fights Joseph off and runs to find Jude. She finds him in the basement possessed and wearing the Brahms mask, getting ready to kill Liza. She tries to appeal to Jude from within, but Sean runs in and smashes Brahms’s head with a mallet, breaking Jude from the trance. Joseph runs in and is mortified, even more so when the spot where Brahms’s head once was is now replaced by a grotesque demonic creature. It creates a blast from the fireplace that kills Joseph. Jude grabs the doll and tosses it into the fire to destroy it for good.
The family moves back to their old home, ready to start over for the better. At night, however, Jude reveals that he still keeps the Brahms mask, and talks as though the doll is still there.