There's a legend out there, about a Sea Temple created by the People of the Water, where the Sea Crown is kept. No one has ever seen this Sea Crown, and very few people even know the story of the temple, except a few members of the People of the Water who wander through the Pokémon world. That all changes when a Pokémon Ranger named Jackie rescues a Manaphy Egg from a greedy pirate named Phantom! Phantom is absolutely determined to snatch the Sea Crown, and he'll need Manaphy to get to it. To stay one step ahead, Jackie will need to enlist the help of the People of the Water.
A chance encounter with the People of the Water puts Ash, May and friends right in the thick of the action, and May forms a very special bond with the Legendary Manaphy, even as the specter of Phantom hovers ever closer! Together, they must find the Sea Temple before Phantom does, unlocking the secret that connects Manaphy and the Sea Temple!