While Ash is doing some special training at Cynthia’s house in preparation for the Unova League, the villains of Team Rocket are finishing preparations to launch their latest diabolical scheme: Operation Tempest!
After watching a training battle, Meloetta wants in on the action. Ash and Krookodile have just accepted Meloetta’s challenge when an enormous Golurk descends upon the battlefield, ridden by its Trainer, Larry—who immediately accuses Ash of being a villain and kidnapping Meloetta! The misunderstanding is quickly sorted out, and Larry explains that he’s one of Meloetta’s protectors, and that he and Golurk have been looking for the Mythical Pokémon for quite some time after it was taken away by some unknown villains.
The villains in question quickly make themselves known: a pair of Team Rocket agents have tracked Meloetta to Cynthia’s house, intending to recapture it! Larry says he and Golurk will battle them while Ash and the others get Meloetta out of harm’s way. The group begins their run—but their path is soon blocked by Jessie, James, and Meowth! Iris and Cilan stand against them while Ash, Pikachu, and Meloetta go on alone.
Unfortunately, they’re playing right into Team Rocket’s hands, and the Boss is waiting to apprehend them! Giovanni and his Persian trap Ash and Pikachu in a cage, and he orders Meloetta to surrender or watch its friends be hurt. Meloetta has no choice, and the three of them are taken onto Team Rocket’s helicopter, then transferred into a submarine that descends to a ruined temple at the bottom of Undella Bay.
Ash watches helplessly as Meloetta is restrained inside the temple. Dr. Zager begins to play a recording of Meloetta’s haunting song, which unlocks an ancient seal, transforming the temple and raising it to the surface of the bay. As soon as the path is clear, Giovanni makes his way to the innermost part of the temple and claims the Reveal Glass—a mystical mirror with unknown powers! What is Operation Tempest really about? Could this be the greatest threat the Unova region has ever faced?!