Ash Ketchum, his loyal pet Pokemon Pikachu and several others travel to an island in search of Celebi, a rare species of Pokemon. The creature is thought to be able to travel through time. However Vicious is also looking for Celebi.

Ash (Veronica Taylor), Pikachu (Ikue Ootani) 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. Two Pokemons join them on their adventure, a brother/sister pair named Latias (Megumi Hayashibara) and Latios (Masashi Ebara) who are protecting the Droplet of the Heart - a valuable treasure.