When the pressure to be royally perfect becomes too much for Mal, she returns to her rotten roots on the Isle of the Lost where her archenemy Uma, the daughter of Ursula from The Little Mermaid, has taken her spot as self-proclaimed queen of the run-down town. Uma, still resentful over not being selected by Ben to go to Auradon Prep with the other Villain Kids, stirs 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, and unleash all the villains imprisoned on the Isle once and for all.