The VKs return to the Isle of the Lost to recruit a new batch of villainous offspring to join them at Auradon Prep. When a barrier breach jeopardizes the safety of Auradon during their departure off the Isle, Mal resolves to permanently close the barrier, fearing that nemeses Uma and Hades will wreak vengeance on the kingdom. Despite her decision, an unfathomable dark force threatens the people of Auradon, and it is up to Mal and the VKs to save everyone...