Ken and Mary of the Pokémon Mystery Club (PMC) are once again looking for a Pokémon from outer space, checking the site of a meteor crash. A Lunatone emerges and zaps them, erasing their memories of the encounter.
Meanwhile, Ash and friends reach Volley Town, finding it strangely deserted. They walk into the Pokémon Center for assistance but Nurse Joy is zoned out and unhelpful. Brock doesn't believe it's the real Nurse Joy.
Team Rocket sneaks into the Pokémon Center, but bump into Ash and friends. When Nurse Joy approaches, they all run, and hide in a storage room. There, they run into the frightened Lunatone. It tries to use Psychic on them, but passes out instead.
Nurse Joy returns to normal and treats Lunatone. It needs moonlight to survive, so they decide to take it up to nearby Camerupt Point where the full moon shines. They hide the Pokémon from the PMC in a cart and pull it up the hill, but are cut off by Team Rocket. Team Rocket gets into a fight with the Pokémon Mystery Club.
The PMC sends Team Rocket blasting off. Pikachu, Mudkip, and Beautifly team up to drive off the PMC, but they won't be defeated. The full moon rises and Lunatone charges up and send the pair off with Hidden Power. The kids then bid farewell to Lunatone.