Jake Wheeler, a 14-year-old middle school student from Hackensack, New Jersey, purchases a vintage Good Guy doll named Chucky in a yard sale to use him in his personal contemporary art project. Jake's father, Lucas, disapproves of this hobby and, after an awkward dinner with some relatives, destroys the project. Jake takes Chucky to school the next day, hoping to sell it at a good price; he is then bullied by Lexy Cross, his cousin Junior's girlfriend. At night, Andy Barclay calls Jake and suggests caution with the doll. Upon confirming that Chucky works without batteries, Jake throws him away. Chucky tracks Jake down to the school talent show and forces him to fake an act of ventriloquism. During the show, Chucky publicly humiliates Lexy, and Jake is subsequently suspended from school for his horrible performance. Later on, Lucas hits Jake after a heated argument over his sexuality when he got a phone call from his teacher; Chucky murders Lucas soon after when he vomits the whiskey he had drunk from Lucas' bottle at his bare feet, which touches an exposed electric cable and electrocutes him in the basement. Jake is taken to live with Logan and Bree, Junior's parents, and Chucky proposes the prospect of killing Lexy too after he came to life in front of Jake and told him that his father deserved to die for always being abusive towards him.

Jake returns to school after his father's death, where he's invited to his classmate Oliver's Halloween party. While everyone is out, Chucky murders the Wheelers' maid. Jake confronts Chucky, who feigns innocence, and tries to convince Jake that he is on his side. That night, Junior and Jake overhear Logan and Bree discussing if they are even capable of looking after Jake, and Junior begins to fear Jake is capable of hurting Lexy. On the night of the Halloween party, Lexy is told to take her sister Caroline - who has begun to fixate on Chucky since seeing him in the talent show - trick-or-treating - but takes her to the party instead. Jake decides to stay home until he finds Chucky missing and races to the party. There, he finds Lexy dressed up as his father, mocking his death. Despite his rage, Jake stops Chucky from killing her. That night, Chucky once again tries to convince Jake to become a killer.

Chucky persuades Jake to give in to his temptation to kill Lexy, remembering his encounter with an unknown serial killer assailant in 1965. Jake attempts to murder Lexy in the woods, only to encounter Junior, who later tells Lexy to apologize to Jake because he worries about what Jake is capable of. Because of this and Caroline's outburst of wanting Chucky, Lexy apologizes to Jake in hopes of having Chucky calm her sister down. Jake originally declines, but after Chucky decides to kill Lexy himself, Jake accepts and seemingly gives him up. Meanwhile, Logan and Bree are called into a meeting alongside Lexy's parents, Hackensack's mayor Michelle Cross and her husband Nathan, due to transpired events. Concurrently, Lexy secretly hosts a rave party with Junior, Oliver, and classmate Devon Evans in attendance. Tensions arise as Junior and Oliver compete for Lexy. Chucky accidentally stabs Oliver when he mistakes him for Lexy and murders him upstairs as the rest of the partygoers are distracted by the blasting music, completely unaware of Oliver's screams. Chucky then corners Lexy in a room, causing a fire that engulfs the house as Jake visits his parents' graves.

As a result of the fire, Caroline ends in the ICU. Lexy and Jake begrudgingly team up to investigate Lexy's burned house for Chucky. Meanwhile, Junior undergoes a medical procedure, and Devon researches the urban legend about how Charles Lee Ray turned into a Good Guy doll. At Lexy's house, Jake saves her from falling from the railing despite Chucky's attempts to convince him to let Lexy die. A police officer appears after this and takes them and Chucky to the hospital. When the two kids get there, Jake is stopped by Devon's mother, Detective Kim Evans, who strongly believes he's behind the murders. At the hospital, Chucky murders the officer who found him. Devon finds Lexy and tells her the truth about Chucky. As Jake is being interrogated, Chucky unplugs Caroline's monitor, causing chaos in her hospital room. The officer's body is found, and Jake, Lexy, and Devon watch as Chucky flips them off from a distance.

When the Cross family returns home, Nathan gives Caroline a Good Guy doll named Tommy, in replacement for the burnt-up Chucky. Jake, Devon, and Lexy ambush the burnt Chucky in a trash can and kick him to his apparent death. Believing Chucky is dead, they move on with their lives, and Jake and Devon have their first kiss. At a Hackensack hotel, Tiffany Valentine and a possessed Nica Pierce are seen living there with two male victims, one who is already dead, held hostage. The two get into an argument that leads to Nica temporarily regaining control of her body. She attempts to free the surviving victim until she returns under Chucky's spell and slashes his neck. Bree talks to her therapist about her stage 4 cancer diagnosis and promises to come clean to her family. Mayor Cross and Detective Evans hold a town meeting at the school, showing remorse for events that transpired and including announcing new city rules. However, things quickly become disastrous when the school principal's severed head rolls onto the stage. Chucky is revealed to be alive, having transferred his soul into the Tommy doll.

After the events of Cult of Chucky, Andy and his foster sister Kyle have begun to hunt down the remaining Chucky dolls. Jake, Devon, and Lexy watch as their biology teacher, Mrs. Fairchild, is arrested and charged for the deaths of Oliver and the principal; with no other option, Jake and Devon successfully contact Andy and Kyle. Meanwhile, Nica reverts to her original body and feigns Chucky in Tiffany's presence. However, Tiffany discovers the ruse and reveals that she has purchased Chucky's childhood home before knocking Nica out and tying her up inside the house. Bree comes clean about her cancer diagnosis to her family; during a meeting with her therapist, Chucky pushes a cart toward Bree and throws her out the glass window to her death. Bree's therapist attributes it to depression and labels it as suicide. Devon reveals his relationship with Jake to his mother; shortly after, Jake, Devon, and Lexy set up a trap for Chucky, who attacks the trio and murders Detective Evans by breaking her neck when she falls down the stairs.

At Bree's wake, Junior blames Jake for the recent deaths. Tiffany shows up unannounced and kisses Logan. Andy abandons Kyle at a gas station and heads to Hackensack on his own. Devon prepares to leave the town and live with his aunt, following his mother's death. At a public conference, Mayor Cross announces that the annual town screening of Frankenstein will have a celebrity guest of Jennifer Tilly, with Tiffany posing as her. Chucky acquaints Junior and convinces him to kill those he believes is responsible for his family falling apart. Jake steals money from Logan and runs away from home; however, he changes his mind after buying a suspicious Good Guy doll and brings it to Lexy's house. Both kids seek out Devon's location and realize that he has broken into Chucky's childhood home. Meanwhile, Chucky, who has regained power over Nica's body, takes Devon hostage. Chucky convinces Junior that Logan cheated on Bree with Tiffany, somehow causing her "suicide," and proceeds to beat Logan to death with the doll. As Jake and Lexy prepare to head to Devon's location, the doll Jake brings begins to come alive. Andy arrives at the Wheeler's house, and Devon is revealed to be surrounded by a horde of Good Guy dolls.

The doll Jake brought to the Cross house comes alive, but he is shot to death by Kyle, who reveals Chucky's voodoo abilities before drugging Jake and Lexy to keep them safe. When Tiffany arrives home, Chucky, as Nica, attempts to kill her, but Chucky and Junior arrive to handle the situation. Tiffany shows Chucky his horde of Good Guys dolls to fulfill Chucky's plan: the dolls will be distributed in a delivery truck to murder people all over the country. When Tiffany accuses Chucky of being self-centered, Chucky tells Junior to kill Nica, but Tiffany, fed up with Chucky's abusive and neglectful treatment of her, decapitates the doll before he can. Tiffany plants a bomb in the basement, which goes off and seemingly kills Andy and Kyle. At the Frankenstein screening, Chucky hides under the theater seats and begins stabbing and killing multiple guests, including Nathan. Lexy convinces Junior to do the right thing, so he stabs Chucky before being stabbed himself. Jake finishes Chucky by crushing his head. Junior apologizes before dying in Lexy's arms. Andy, who survived the explosion, hijacks the truck and foils Chucky's plan, but Tiffany's doll form reveals herself and takes him hostage with a gun. The following day, Tiffany reveals that she has cut off Nica's limbs in fear of what Chucky would do if he takes over Nica's body again. Jake, Devon, and Lexy visit the Wheeler family's graves before a gloved hand appears. In an epilogue, Chucky recaps the series' kills and ends the season finale.