Plot
The film begins focused on a small baseball park as a father and his daughter Emily (Frankie Corio) play catch. The two discuss the girl's recent nightmares and the importance of growing up. The father takes the girl to the car where boxes have been prepared of her toys for donation. Encouraging her to make a mature decision, the father leaves to return the baseball equipment and the girl remains by the car. Deciding to give up her well-loved stuffed rabbit, the girl places it in the box as the lights in the parking lot begin to go out. Feeling afraid, the girl runs to the equipment room where she finds her father incapacitated on the floor. She is then grabbed and her bones are broken as she is forced into a bag by a mysterious cloaked figure.
Four weeks later, Patrick McKee (Sam Claflin) and his wife Karina (Antonia Thomas) have just moved into to Patrick's childhood home with their young son Jake (Caréll Rhoden). This home, located in a small town bordering a large forest, is near to Patrick's family's lumber yard where he works with his brother Liam McKee (Steven Cree). During dinner, Patrick tells Liam about his prototype for a machine with the ability to delimb trees automatically. Patrick finishes by mentioning needing some money to get his prototype off the ground, potentially by getting a loan extension. Liam mentions Patrick's money troubles and encourages him to put his dreams aside and focus on getting out of debt. That night, Patrick struggles to sleep, hearing noises in the woods behind his home and nightmares about his son being kidnapped.
The next day, Patrick goes to work with his brother at the lumber yard. He reminisces about spending time at this lumber yard as a child with his brother and father. In his memories, their father seems concerned for his sons' safety. Further memories show young Patrick and Liam exploring areas that used to be used for copper mining as Patrick whittles an owl out of wood using a small pocket knife. Eventually finding an abandoned mineshaft, the boys initially seem curious but quickly become afraid of the area. However, young Patrick notices a tree near the opening of the mine which is supposed to be the softest wood (and therefore the best for carving). While attempting to cut some wood off of the tree, a mysterious figure reaches out from the dark mine opening, cutting off a piece of young Patrick's hair. The boys run away in a panic, Patrick leaving the wooden owl and his baseball hat behind.
In present day, Karina is working from home while Jake plays with a wooden recorder whittled by his father. Karina, focused on her work, does not notice as Jake is lured into the woods by a doll waving from the trees. Upon noticing her son is gone, Karina runs panicked into the woods, calling his name. Eventually hearing the recorder, Karina follows the sound to find her son alive and well deep in the woods. She takes him home.
That night, Patrick receives an email while whittling. The email informs him that his loan extension has been denied and repayments are past due. Frustrated and overwhelmed, Patrick breaks his whittling knife on his desk in a fit of anger. While throwing away the broken knife, he finds the owl he whittled as a child in his desk trash can. Later, unable to sleep after another nightmare, Patrick is awake as the power goes out and the house is broken into. Patrick tells Karina he can hear the sound of a large bag being zipped open and closed outside. He runs outside and yells for whoever is out there to face him as Karina calls the police. The police arrive quickly and investigate. They find footprints outside Jake's second story bedroom window, as well as small whittled figurines which they believe have been used to be thrown at his window to get the child's attention. The family gets a security system installed that day.
Patrick returns to the lumberyard and relives further memories of his youth. He remembers his father speaking to him about the history of the Bagman. Patrick's father cautioned that the land belonged to the Bagman, and this creature loved well behaved children with dreams and aspirations. Warning his son to never let the Bagman get close, as he can use a lock of your hair to find you anyplace, anytime. That night, frustrated by the constant recorder sounds, Karina asks Patrick to hide Jake's recorder. Patrick, distracted, accidentally places the recorder in the trash pile. Later that night, they are unable to find the recorder which Jake asks for.
After another nightmare about Jake getting kidnapped by the Bagman, Patrick jolts awake. Once again the power goes out and Patrick goes outside to investigate. While outside, he finds his garage door open. Inside the garage he finds a creepy doll wearing the baseball cap he lost as child. Startled, Patrick moves to go inside but the door has been locked from the inside. While attempting to get inside through the dog door, Patrick sees a hooded figure crouching on his living room ceiling. The figure plays Jake's recorder as Patrick breaks his window and rushes inside. Upon calling the police, they are unable to find any fingerprints or proof of breaking or entering, but their investigation into the power outages confirms there is no logical reason for the multiple power outages.
Karina and Patrick discuss the possibility that there is no assailant but these are all manifestations of Patricks' childhood paranoia, with Karina blaming Patrick's father for putting terrible ideas in his head. Karina and Patrick go to Patrick's old child psychologist Barbara (Sharon D. Clarke) as Karina's sister Ana (Adelle Leonce) watches Jake. Barbara, with Patrick's permission, recounts the fears which plagued Patrick as a child, all concerning a mythical creature called the Bagman. Barbara explains Bagman folktales exist all over the world and it is a common imaginary creature. While showing the many childhood drawings Patrick made of dark figures in the woods, Patrick has another memory of his father. He remembers his father in his room, explaining the legend of the bagman has been passed from father to son for generations. He goes on to explain the Bagman feeds on fear and anxiety, but there is a way to avoid the Bagman. Patrick's father explains the love of a child has a type of magic, and a child's most loved item can absorb that magic and protect them. Patrick's father explains as long as young Patrick holds on to his most loved item, he cannot be hurt by the Bagman.
While at Karina and Patrick are at dinner in an attempt to put childhood fears to rest, Ana is attacked by the Bagman at her home. Karina and Patrick arrive just as the police are interviewing a traumatized Ana and comforting a scared Jake. Realizing the threat is real, Ana, Jake, Karina, and Patrick go to Liam's home with a police escort. That night, Patrick hears sound from the baby monitor and finds Liam, his wife, and all the police sedated. Patrick hears his son crying for him outside as he sees a shadowy figure with a large bag sprint down the street. Giving chase and following the sounds of his son's cries, Patrick follows the Bagman back to the abandoned mineshaft. Following the sounds of his son, Patrick squeezes through a small hole to find a side chamber. This chamber is full of small shrines, each one has a lit candle in front of a basket of sticks which hold a small toy. While investigating, Patrick finds the Bagman's bag, hanging on a hook. Inside Patrick finds the doll. While investigating the doll, Patrick discovers it has a voice box which was able to play Jake's cries. The Bagman attacks Patrick, sedating him and taunting him with Jake's recorder. Eventually revealing a basket with Patrick's broken pocket knife, Patrick finally realizes he was the Bagman's goal. Back at Liam's house, Karina wakes to find Patrick gone but Jake is still in bed. Realizing what happened, she calls the police.
Patrick grabs the shards of his pocket knife and stabs the Bagman who retreats. Grabbing Jake's recorder, Patrick stumbles back toward the entrance of the mineshaft which is now gated and locked. Attacked by the Bagman once more, Patrick uses the last of his strength to throw Jake's recorder out of the mine. The Bagman grabs Patrick and breaks his bones to fit him in his Bag. Karina and the police arrive at the locked mine but are unable to find Patrick. Karina, finding the recorder, realizes the sacrifice Patrick made to keep their son safe.
Karina and Jake are seen packing up their belongings and driving away. As they do, Karina explains to Jake how much his father loved him and how important it is that he never loose his recorder.
