When the pressure to be royal becomes too much for Mal, she returns to her rotten roots on the Isle of the Lost. There, she finds that her archenemy, Uma, daughter of Ursula, has taken her spot as self-proclaimed queen of the run-down town. Uma, still resentful over not being selected to go to Auradon with the other Villain Kids, directs her pirate gang, including Captain Hook's son Harry and Gaston's son Gil, to break the barrier between the Isle of the Lost and Auradon...unleashing all the villains imprisoned on the Isle, once and for all.