Mal struggles with her new celebrity life as the girlfriend of King Ben, dying her hair blonde, and maintaining a princess-like personality that she is uncomfortable with. She admits her issues to her friends Evie, Carlos, and Jay, but they are content with their new lives in Auradon and do not wish to return to the Isle of the Lost. Evie scolds Mal for relying on her mother’s spell book to solve her issues. Carlos, wishing to ask Jane to the upcoming Cotillion dance, turns to Mal for help to be honest with her. Mal gives him a sweet that will make him speak the truth, but his dog Dude eats it, magically speaking the truth in English and very frankly as a result.
Ben eventually discovers Mal’s reliance on magic, and she comes clean about her insecurities, causing the two to have a falling out. Mal returns to the Isle, now ruled by her former friend Uma, Ursula’s daughter, along with Harry and Gil, the sons of Captain Hook and Gaston. Mal visits hair stylist Dizzy Tremaine, Drizella’s daughter, who restores her signature purple hair, saying she felt that Mal’s blonde hair was unnatural. Harry discovers Mal has returned and informs Uma.
Ben, Evie, Jay, and Carlos learn of Mal’s departure and sneak onto the island to find her, but Gil recognizes them. Ben confronts Mal, who rejects his feelings for what she thought was both his sake and Auradon’s. Ben leaves dejected, only to be captured by Uma, who orders Mal and her friends to retrieve the Fairy Godmother’s wand or Ben dies. Carlos and Jay return to Auradon Prep, where they create a replica of the wand using a 3D printer. They are caught by Lonnie, who blackmails them into letting her come with them, having previously been rejected from Jay’s sports team based on her gender.
Uma speaks with Ben, bitter that she and the others were not chosen to go to Auradon. Ben takes this into account and invites her to Auradon, but Uma instead plots to make her own way there. Mal’s group return, handing over the fake wand in exchange for Ben, but Uma realizes it is a forgery. The group flee back to Auradon, but Mal and Ben’s relationship is still on the rocks. The villains’ children come to terms that they cannot run from their pasts and agree to be honest with themselves and each other. Carlos confesses to Jane and they become a couple, while Jay appoints Lonnie as the captain of his team.