Six years after the events of Bride of Chucky, Glen, the kind and gentle son of Chucky and Tiffany, has a nightmare in which he murders a little girl’s parents. In reality, he is living a life of embarrassment and abuse as a ventriloquist’s dummy from his own point of view. Desperate to know his parents, Glen tracks Chucky and Tiffany down to Hollywood, where they are first shown killing a man who is dressed as Santa Claus for a movie. Upon tracking down his mom and dad, who are now dummies in one of Jennifer Tilly’s films, Glen uses a voodoo amulet to bring them back to life. When Chucky (voice of Brad Dourif) finds out that Glen is his child, he faints, while Tiffany is ecstatic and hugs her child. Tiffany and Chucky argue over whether Glen is male or female, due to their lack of genitals. Chucky decides to continue labeling him as a boy, whereas Tiffany labels him as a girl, calling him “Glenda”.
When a puppeteer Tony Gardner (designer) begins taking Tiffany apart, she and Chucky decapitate him with a piano wire. Jennifer Tilly sees the beheaded body and calls the police. Chucky, Tiffany, and Glen follow her home. Glen, having witnessed his mom and dad kill the puppeteer, asks them why they murder others, as he feels that violence is bad. Tiffany and Chucky make an agreement to quit killing, although Chucky only pretends to agree, crossing his fingers behind his back hoping to get Tiffany to shut up.
Jennifer tries to get a role as the Virgin Mary in Redman’s directorial debut, but after Redman says that Jennifer isn’t right for the part, she invites him over to her house. Chucky and Tiffany make plans to transfer their souls into Redman and Jennifer. Jennifer and Redman start to make love, only for Tiffany to knock them out. While they are unconscious, Tiffany inseminates Jennifer with Chucky’s semen. Chucky leaves and takes Glen with him. After driving Britney Spears’ car off the road, killing her, they proceed to go to a photographer’s darkroom. The photographer, Pete Peters (John Waters), had taken pictures of Tilly kissing Redman, and of Chucky masturbating. Glen tries to warn Peters that Chucky will kill him, only for Peters to bump into a shelf, causing a jar of acid to fall and accidentally kill him. Chucky, overjoyed, believes Glen did this on purpose and takes a picture to celebrate, much to Glen’s and Tiffany’s dismay.