In Leonardo, New Jersey, Jay and Silent Bob (Jason Mewes and Kevin Smith) are getting by through growing marijuana in the old RST Video Store, disguised as a chicken sandwich restaurant called "Cock Smoker". They are raided by a SWAT team and taken to court where they are appointed a lawyer (Justin Long), who makes them sign a document before the trial begins. The lawyer then convinces the judge (Craig Robinson) that their business was actually a temporary pop-up shop promoting an upcoming movie. Jay and Silent Bob win their freedom, but another trial immediately begins. The lawyer switches sides, defending a representative of Saban Films, who optioned Bluntman and Chronic. As Saban is planning a big-budget reboot, Bluntman v Chronic, the lawyer claims that Jay and Bob had legally signed away their naming rights to Saban, and thus cannot self-identify as "Jay and Silent Bob" ever again.Furious, Jay and Silent Bob visit Brodie Bruce (Jason Lee), whose store, Brodie's Secret Stash, now operates at the abandoned mall. He tells them about the Bluntman and Chronic reboot, which is being directed by Kevin Smith. The film is largely completed already, but a large action scene is to be shot at the annual fan convention Chronic-Con in Hollywood. Jay and Bob have three days to get to Los Angeles to stop the film from being completed and win back their identities. When the two learn that they are on a No-Fly List, they steal an arrogant businessman's (Ralph Garman) credit card information and order a Ride Me Now to California.They arrive in Chicago, but when the driver (Fred Armisen) confesses that he has never smoked marijuana, Jay gives him a joint to enjoy as his first. He smokes outside of Mooby's, where he is immediately arrested while Jay and Bob are distracted. After placing an order, Jay looks at a nearby TV and recognizes Justice (Shannon Elizabeth), his former girlfriend, who is now a weatherperson. Jay and Bob find where Justice lives and pay her a visit. Justice faints in surprise and the duo are then knocked out and taken prisoner by a girl wearing a hockey mask. They awaken, tied up in Justice's living room, where Justice tells Jay he left her heartbroken by never visiting her in jail. She has since married and given birth to their love child, named Millennium Faulken (Harley Quinn Smith). She introduces Jay to their daughter, but urges Jay to never reveal his identity to her. Outside, Millennium (known as "Milly"), revealed to be the same masked girl from earlier, introduces Jay and Silent Bob to her best friend Soapy (Treshelle Edmond), who is deaf and communicates in sign language.Justice leaves for vacation with her wife Reggie (Rosario Dawson), and Milly forces Jay to take her to Hollywood with him and Bob. They reluctantly agree and take the ride-share. Milly drugs Jay and Bob with a very strong edible, which leads to a dream in which Jay receives parenting advice from Redman and Method Man, the stars of Jay's favorite film How High. They wake up on a highway in New Orleans, where they meet Milly's two other friends, Jihad (Aparna Brielle) and Shan Yu (Alice Wen). They tell Jay that they want to visit Chronic-Con because Shan Yu, an immigrant from China, is a huge fan of the first Bluntman and Chronic film and it is her dream to attend Chronic-Con before she has to return to China. They steal a van from a victim Milly seduced through a pedophile chat-room and drive to California. Jay, wanting to be protective of his daughter, asks about her friends. He learns that Jihad was brought to America after her brother tried to kill her for being sexually assaulted. Milly admits that her behavior is attributed to her never knowing her father.Jay and Bob are abandoned once again at a Mooby's, and are confronted by their first ride-share driver, angry at the two for ruining his life. Jay and Bob steal his car and search for the van. They find the van in a vacant area, where the Ku Klux Klan are having a rally. They have kidnapped the girls and plan to kill them. Bob steals a klan hood and passes himself off as the new Grand Dragon to distract them while Jay rescues the girls. In the van, they throw a portable toilet at the Klansmen, covering them in feces, and the group flees from the scene. They make it to California, where Jay tries to bond with Milly, still never revealing their relation per Justice's wishes. They make it to Chronic-Con where they sneak in. Jay and Bob split with the girls, as they plan to ruin the shoot, but the girls want to be extras in the film to fulfill Shan Yu's dream. They agree to part ways, with Jay hugging Milly and letting her know he is proud of her.Jay and Bob try to sneak past a familiar security guard (Diedrich Bader), who chases them through panel after panel. They hide in an empty panel room where they are met by Holden McNeil (Ben Affleck). He has just finished recording a podcast with Alyssa Jones (Joey Lauren Adams), who is adapting Holden's Chasing Amy comic into a Netflix original series. The two have maintained a platonic friendship over the years and Holden has donated his sperm to Alyssa and her wife (Virginia Smith) so they may have a child, whom he helps co-parent. He introduces Jay and Bob to their daughter, Amy (Logan Lee Mewes). Holden tells Jay that fatherhood gave him a new purpose in life. This inspires Jay to abort their mission and be a father to Milly. Holden gives them VIP badges, which grants him and the girls access to the panel with Kevin Smith. After showing a clip of the film, Smith goes backstage to take a break before shooting the big scene. Noticing that Bob bears a great resemblance to Smith, Milly sneaks backstage and knocks out Smith, giving Bob Smith's clothes to disguise himself. They bring Milly and Shan Yu on stage to film the scene, but Shan Yu sees through their ruse and knocks Bob unconscious, bringing out the real Kevin Smith. Bob is thrown out of the hall and Shan Yu reveals herself to be a Russian spy, bent on destroying American pop culture conventions. After Jay insults Shan Yu, she turns her gun on him, at which point he reveals to Milly that he is her father. Bob regains consciousness outside and steals a large metal "Iron Bob" suit that was to be used in the filming of the scene. Controlling the suit, Bob incites a riot at the panel and disarms Shan Yu and her henchmen.After making their way back home, Jay shows Milly the Quick Stop. Bob brings them coffee as Jay tells Milly his stories of his and Bob's adventures, including meeting Justice. Dante Hicks (Brian O'Halloran) arrives to open Quick Stop and bemoans the fact that the steel shutters are once again jammed closed.In a post-credits scene, Jay tells Milly that for the past twenty-five years, he and Bob have been pulling pranks on Dante by jamming gum in the locks.