Mal, Evie, Carlos, and Jay return to the Isle of the Lost to recruit a new batch of villainous offspring to join them at Auradon Prep, but when Hades, the former god of the underworld, almost breaches the barrier when they go back to Auradon, Mal fears that an unwelcome villain could wreak vengeance on the kingdom and her peaceful life. Mal resolves to permanently close the barrier to save everything she loves, but an unfathomable dark force unexpectedly...