Pokemon Movie 05: Mizu no Miyako no Mamorigami Latias to Latios

Satoshi, Kasumi, and Takeshi arrive in the beautiful canal city of Altomare, where a Water Pokémon race leads Satoshi into an encounter with a mysterious girl. He soon learns that she is actually Latias in disguise, one of two legendary Pokémon who secretly protect the city together with Latios and the sacred Soul Dew.

Thieves Zanner and Lyon target the guardians and the Soul Dew in order to control Altomare's ancient defense system. Their plan turns the city's own power against it, forcing Satoshi and his friends to protect Latias and Latios before the machinery meant to defend Altomare becomes the cause of its destruction.