Gekijô-ban poketto monsutaa: Mizu no Miyako no Mamori Gami Ratiasu to Ratiosu

Ash, Pikachu and the rest of the Pokemon gang try and stop a pair of thieves hiding out in the canals and alleyways of Alto Mare, the water capital of the world. Joining the adventure are two new Pokémons, a brother/sister pair named Latias and Latios who are protecting the Droplet of the Heart - a valuable treasure.