Mal, Evie, Jay, and Carlos return to the Isle of the Lost to select four new villain kids (VKs) who will be brought to Auradon. Their choices are Dizzy, the granddaughter of Lady Tremaine; Celia, daughter of Dr. Facilier; and Squeaky and Squirmy, the twin sons of Mr. Smee. The momentous day arrives for the VKs to be collected, and at the same time, Mal’s longtime boyfriend Ben, now king of Auradon, proposes. Mal accepts, inviting a future that blends both their worlds. Yet teeming jealousy flares up as Audrey, Ben’s former girlfriend, resents the shift in power and the sense that the royal family’s legacy is slipping away. Queen Leah, Audrey’s grandmother, admonishes her for failing to secure the family’s future by marrying Ben, adding to the tension.
As the elder VKs return to Auradon with the newest arrivals, an ominous sign appears when Hades tries to breach the Isle’s protective barrier. Mal steps in to stop him, an act that leaves her weakened. The barrier’s existence becomes a focal point: the idea of permanently closing the Isle to protect Auradon gains traction, a plan that stirs further conflict among the VKs.
Audrey’s resentment boils over in a dramatic turn when she steals the Queen’s crown and Maleficent’s scepter from the museum, gaining dangerous magical powers and sliding into villainy. With the theft and Hades’ break-in attempt, Mal suggests that the safest course is to seal off the Isle forever, a move that would separate the VKs from their parents and loved ones.
In a bold but dangerous move, Audrey curses Mal using Maleficent’s scepter, transforming Mal into an elderly version of herself. Mal, the other VKs, and their friends hurry back to the Isle to secure a vital artifact—Hades’ ember—the only power strong enough to break the curse and reclaim Mal’s true form. Celia helps guide them into Hades’ lair, but the plan hits a snag as Hades proves elusive. The Ember becomes a key symbol of power, and its secrets are shared with Mal: Hades reveals he is her absentee father, and warns that the ember must not be wet to unleash its full magic; as a “half Hades,” Mal may not receive all the power Hades can command. He finally hands over the ember, but cautions them to use it wisely.
Leaving the Isle, Mal and her companions are intercepted by Uma, Gil, and Harry, who offer their help after Mal falsely agrees to release all the children from the Isle. Meanwhile, in Auradon, Audrey crashes Jane’s birthday party with a sleeping curse, while Chad leans toward her, and Jane hides in the enchanted lake. Audrey’s dark magic spreads, turning the kingdom under her spell and prompting her to offer a reversal if Ben agrees to marry her. When Ben refuses, Audrey curses him into a beast and begins turning people to stone.
The VKs—led by Mal and Uma—return to Auradon with their friends and wrestle with their competing desires for leadership. Yet their shared goal drives them to join forces to confront Audrey. A crucial moment occurs when Carlos helps calm the beastly Ben, removing a splinter from his hand, and Jane heals him with enchanted lake water, restoring his humanity. Back at Evie’s house, Mal and Uma begin to repair their fractured friendship, and Evie awakens Doug with true love’s kiss. Audrey traps the friends in the house, but their combined magic allows them to reverse the spell and reunite.
At the Fairy Cottage, they encounter a shell-shocked Chad. Mal confesses her plan to seal off the Isle, leaving Celia to confront the painful reality that she might never see her father again. The ember is dropped into water, and Uma walks away, signaling a fracture in their alliance. Evie challenges Mal for lying to their circle, and suddenly Ben, Carlos, Evie, and Jay are turned to stone, amplifying the crisis.
Audrey seizes Celia and launches a vicious assault. Mal responds by transforming into her dragon form to protect her friends. In a pivotal turn, Uma returns and merges their magic with Mal’s to reignite the ember, allowing Mal to turn the tide. Audrey is defeated and falls into a deep coma, and the curses are lifted. Mal urges Hades to use the ember to revive Audrey, and while Hades performs the revival, he criticizes the double standard that forgives Audrey due to her not being labeled a villain. Audrey awakens, and she and Mal begin to repair their relationship, with Ben also making amends.
Faced with the need for a broader solution, Mal shifts her aim from simply ruling Auradon to bridging both worlds. With Ben’s blessing and support from Fairy Godmother, she replaces the barrier with a literal bridge, connecting Auradon and the Isle. The people celebrate this new merged society, where former foes can coexist.
In the aftermath, the romantic and friendship dynamics settle into a new balance: Evie is with Doug, Carlos with Jane, Mal is engaged to Ben, and Jay and Gil plan to travel the world together. Audrey begins to form a tentative romance with Harry after Uma declines him. In a mid-credits scene, Mal, Evie, Jay, and Carlos race across the new bridge toward the Isle to reunite with their parents, signaling a reconciled future for both sides of the fairy-tale world.
