A mother gives her 13-year-old son a toy doll for his birthday, unaware of its more sinister nature.
Andy Barclay is a lonely boy living with his mother Karen. She brings him a gift, the Buddi doll, which is supposed to be the perfect AI companion for children. Andy ends up getting Chucky, a defective Buddi doll that had been programmed with his safety features turned off. Although Chucky wants to be Andy’s best friend, his methods become increasingly dangerous.
Chucky sees that Karen’s boyfriend Shane is a jerk to Andy, and after hearing the boy wish Shane was gone, Chucky obliges by killing Shane and giving Andy the man’s skinned face on a melon as a gift. Andy and his friends Falyn and Pugg try to get rid of Chucky, but he is found and reprogrammed by the building’s creepy electrician Gabe, whom Chucky kills as well.
After Chucky kills the mother of Detective Mike Norris, Andy tries to convince Karen that Chucky is evil, but she doesn’t believe him. She takes Andy to work on the night when the Buddi 2 dolls are launching, but Chucky manages to hack into all products from the same company that made him, and he makes the other dolls terrorize the customers. Andy, Mike, and Karen all fight Chucky and succeed in destroying him, and Andy and his friends demolish his remains to ensure he won’t come back.
As all the Buddi dolls are set to be recalled, one is seen with its eyes glowing red, just like Chucky.
At the Kaslan Industries “Buddi” assembly factory in Vietnam, a male employee is chastised and fired by his supervisor for insufficient work. In response, the employee uses a computer at his workstation to tamper with the doll he is assembling, disabling all of the safety features. As this particular Buddi is packed alongside others in preparation for international delivery, the employee commits suicide.
In Chicago, Illinois, Zed-Mart clerk Karen Barclay (Aubrey Plaza) and her 13-year-old hearing-impaired son Andy (Gabriel Bateman) are settling into their new apartment, where Karen encourages Andy to make new friends as she works to prepare for his upcoming birthday. In an attempt to cheer Andy up and make up for the unease caused by the move, as well as the presence of her new boyfriend Shane (David Lewis), Karen blackmails one of her work colleagues in order to procure a defective Buddi doll and presents the toy to Andy as an early birthday gift. Once Andy activates the doll, it names itself Chucky (voiced by Mark Hamill) and becomes very attached to Andy. As the two bond, Chucky helps Andy befriend two other children in the building – a girl named Falyn (Beatrice Kitsos) and a boy named Pugg (Ty Consiglio) – and even frightens Shane on Andy’s request. Over time, however, Chucky begins to display violent tendencies. He strangles the Barclays’ pet cat after it scratches Andy, and as Andy and his friends gleefully watch The Texas Chainsaw Massacre 2 one night, Chucky starts mimicking the violence on the screen and approaches the trio with a kitchen knife, before Andy disarms him.
Andy arrives home the next day to find that the cat is dead, and Chucky admits to murdering it so that it wouldn’t hurt him anymore. Further antics cause Karen to lock Chucky in a cupboard despite Andy’s pleas, but he escapes and further terrorizes Shane, which leads to Shane confronting Andy. After overhearing Andy’s pleas for Shane to disappear, Chucky follows him home, where it is revealed that Shane has a family and has been cheating with Karen. While Shane is outside taking down Christmas lights, Chucky frightens Shane into falling from the ladder and breaking both of his legs. Chucky then activates a tiller which runs into Shane’s head, killing him. By the following day, Chucky has delivered Shane’s skinned face as a gift, to Andy’s horror.
While police detective Mike Norris (Brian Tyree Henry) and his partner Willis (Nicole Anthony) begin an investigation, Andy, Falyn and Pugg decide to disable Chucky and dispose of him in the garbage. Building voyeur and electrician Gabe intercepts the doll and takes him to the building’s basement to prepare him for online sale. Now fully repaired, Chucky demonstrates his ability to remotely interface with other Kaslan products and torments Gabe before mutilating him with a table saw. After making his way back to ground level, Chucky ends up in the possession of another kid in the building, Omar (Marlon Kazadi) and ultimately proceeds to kill Mike’s mother down the hall, Doreen (Carlaese Burke) by causing the Kaslan Car she is travelling in to crash, before stabbing her in the chest. Meanwhile, Andy fails to convince Karen that Chucky has become murderous, and she takes Andy along to her next work shift in order to keep him nearby.
Mike, suspecting that Andy is the killer, travels to Zed-Mart and apprehends him just as Chucky takes control of the store. Havoc ensues as employees and patrons alike are assaulted and murdered by drones and other hacked toys, while Chucky triggers the building’s lockdown sequence. Mike is wounded amid the chaos, and Andy and his friends manage to reach the exit, only for Andy to be lured back in when Chucky reveals that he is holding Karen hostage and plans to kill her. Andy manages to free his mother while under attack from Chucky, before overpowering and defeating the doll with help from Karen and Mike. While paramedics tend to Karen, Mike and other survivors, Andy and the rest of his friends smash Chucky’s lifeless body in a nearby alleyway. In the aftermath of Chucky’s killing spree, Kaslan Industries CEO Henry Kaslan provides a disclaimer regarding Chucky’s programming, and as more Buddi dolls are shown being recalled and placed into storage, one starts malfunctioning inside its box.
The film starts with an ad for the Buddi dolls, made by major tech developer Kaslan Industries. The Buddis can connect to the owners’ electronics system and adapt to their routines to help them in their day-to-day lives. It is set to be a major seller.
At the Kaslan factory in Vietnam, the manager berates one of his employees for slacking on the job. He fires him but also orders him to finish the doll that he has been working on. Out of spite, the employee programs the doll to have all of its safety functions turned off. After sending the doll out for distribution, the employee jumps out a window and lands on his boss’s car.
In Chicago, we meet Karen Barclay (Aubrey Plaza) as she works at her job, ZedMart, where a customer is complaining that the Buddi doll he ordered isn’t blonde like his kid wanted. Karen clarifies that it’s because the doll they are looking for is the Buddi 2 that hasn’t come out yet. Karen goes home to her son, Andy (Gabriel Bateman), who wears a hearing aid. They have settled into a new apartment, and Andy is pretty lonely with no friends. Making things more difficult is that Karen is dating Shane (David Lewis), whom Andy sees as a jerk. Karen and Andy also meet their neighbor, Detective Mike Norris (Brian Tyree Henry), who lives with his mother Doreen (Carlease Burke).
At work, a customer brings back a defective Buddi doll (the same one from before) after complaining that its eyes were glowing red. Karen’s boss Wes (Amro Majzoub) plans to send the doll back so that it can be compacted, but Karen wants to take it home for Andy. When Wes refuses to give it up, Karen blackmails him by reminding Wes that he cheated on his wife, so he lets her have it. Karen brings the doll home as an early brithday gift for Andy, but he doesn’t seem interested in it. Andy turns the doll on, and it starts to speak to him. He tries to name it, but the doll refers to itself as Chucky (voice of Mark Hamill).
Andy has a hard time getting Chucky to do what his functions are supposed to do. He gets commands wrong and inadvertently creeps Andy out by waking him up at night. However, Andy finds that he can talk to Chucky about his feelings toward his mom dating Shane, and Chucky forms a genuine attachment to Andy. He starts to teach Chucky how to scare Shane by showing him how to make creepy faces. Chucky does so, but his recording device also plays back Andy’s words about Shane, which makes him mad when he hears them and gets Andy in trouble with Karen.
On one occasion, Andy’s cat Rooney scratches him. Seeing that Rooney hurt Andy, Chucky begins to strangle the cat until Andy stops him.
Andy befriends two other kids from his building – Falyn (Beatrice Kitsos) and Pugg (Ty Consiglio). They hang out after they see that Chucky is different from the other Buddi dolls (mainly that he mimics Pugg swearing). The kids watch one of the “Texas Chainsaw Massacre” movies, and Chucky begins to imitate Leatherface’s movements by walking toward Pugg menacingly with a knife, before Andy once again has to stop Chucky from hurting anyone.
Andy comes home from school one afternoon and finds that Chucky stabbed Rooney to death for seeing him as a threat to Andy. The boy tearfully tosses his cat down the garbage chute and has to hide from Karen that the doll killed the cat. Chucky tries to make it up by frightening Shane again, but as he plays back Andy calling Shane an asshole, the man goes to Andy’s room to confront him about leaving Chucky around, and to state his problem like a man. Andy is left crying and saying how he wishes Shane would go away. Chucky hears the request, and his eyes glow red as he forms a sinister smirk.
Shane later goes home after arguing with Karen, where it is revealed that he is already married with two kids. He goes outside to take down some Christmas lights, only for Chucky to knock his ladder over and causes him to land on his feet, painfully shattering his legs. With the lights wrapped around him, Chucky gets a tiller and turns it on, which pulls Shane toward it and then scalps him. Chucky then proceeds to slash Shane up. The next morning, Mike and his partner come across the scene to see that Shane’s face has been removed. Karen is later informed, and she learns about his other family.
Andy is given another unwelcome surprise when he goes into his room and finds that Chucky left him a melon with Shane’s skinned face on it as a gift. He plays back the sound of Andy wishing Shane was gone, so he gets Falyn and Pugg and convinces them that Chucky needs to be destroyed. They hold Chucky down, and Andy pulls out his main core before they dispose of him. They then try to get rid of the Shane melon by wrapping it in gift paper to throw down the garbage chute. Unfortunately, they are spotted by Karen, and when Andy says its a gift for Doreen, Karen offers to escort them over to give it to her. Before she can unwrap it, Andy tells her that he would like for her to open it at his birthday in a few days, to which Doreen agrees.
Chucky is found by the building’s electrician/peeping tom Gabe (Trent Redekop), who brings the doll to his little workshop where he puts a new core inside Chucky, with plans to resell him for a lot of money. Gabe then starts to leer at Karen in her bathroom, when the electrical items in the room start to flicker. Chucky starts to reawaken, and he manages to hack into other Kaslan electronic products. He starts to torment Gabe, until he gets him to hang above a buzzsaw. Chucky raises the heat on the pole that Gabe is holding onto until it gets so hot that Gabe falls groin-first onto the saw and is dismembered.
Andy later finds that another boy from his building, Omar (Marlon Kazadi), has found Chucky, but he’s calling him “Chode”. Andy tries to get him back from Omar, but when he refuses, they start to fight until they are pulled off each other. Andy finds Omar’s phone and uses the Buddi app to keep an eye on his friends. He sees through Chucky’s eyes that Pugg has expressed doubts to Falyn about being friends with Andy.
Andy and Karen later go to the Norris apartment for dinner. While there, Chucky is nearby and overhears Doreen refer to Andy as her “new best friend.” When everyone else is out of the room, Andy manages to get the Shane melon away from the apartment and throw it down the garbage chute.
Doreen later goes outside and is picked up by a self-driving Kaslan car. She is driven around near the supermarket, until the car starts going out of control, as it is manipulated by Chucky. He causes the car to crash before he breaks in and stabs Doreen in the chest. Mike later comes across his mother’s body and weeps before he later finds out that the Shane melon was discovered in the chute, and he recognizes the wrapping paper around it.
Karen learns that Andy took Omar’s phone, and he tries to convince her that Chucky is behind all the recent string of incidents, but she doesn’t believe him and takes him to work with her. At the same time, Falyn and Pugg learn about Doreen’s death and suspect that Andy was right about Chucky.
At ZedMart, customers are gathered as the Buddi 2 is about to launch. They storm in like Black Friday as the dolls go on sale, but as Wes comes out in a Buddi costume, he is stabbed in the neck by Chucky. His costume head comes off, and his blood is sprayed all over a terrified little girl. The lights in the store then go out as Chucky takes over all the electronics in the store. He sends drones out after people, and one of them finishes Wes off by slicing into him. The other customers start running around in a panic, and the other Buddi dolls start to come to life. Andy is helped by Falyn, Pugg, and Omar, but Mike shows up and tries to arrest Andy after suspecting him of being involved in Doreen and Shane’s deaths. He soon sees that Chucky is responsible, but Mike gets cut by a drone after saving one of the kids. After taking out several dolls, Andy is faced with Chucky, who says that if he can’t be his friend, nobody can. He then reveals that he has Karen tied up and is going to hang her. As Chucky goes for Andy, the boy starts to sing “The Buddi Song” that Chucky sang earlier, in an attempt to talk him down. It works long enough for Andy to knock Chucky off of him and go save his mom, but Chucky gets up and attacks Andy again. Andy manages to free Karen before grabbing Chucky’s knife and sticking it into his core, seemingly shutting him down for good. But when Andy goes to his mom, Chucky lunges toward him until he is shot by Mike. Karen then finishes off the evil doll by ripping his head off. Medics arrive for Karen and Mike, while Andy and his friends destroy Chucky’s remains in an alley.
An announcement is made by Kaslan’s CEO Henry Kaslan (Tim Matheson), who issues a statement about the Buddi dolls’ programming. The dolls are recalled and placed back into storage. Suddenly, one of the dolls’ eyes start glowing red…