A vast Pokémon habitat amid the hustle and bustle of the big city seems like the perfect new home for a group of five Genesect. The arrival of the Mythical Pokémon quickly become a problem for the city's residents, though. Their nest threatens the city's power supply, and they keep attacking anyone who approaches it. The Genesect don't trust people, and they've found a dangerous ally in the Legendary Pokémon Mewtwo, who sympathizes with them because its own origins also involve human tampering. Their leader, a red Genesect, doesn't want Mewtwo's help, and their confrontation quickly rages out of control. Can Ash and friends stop these two powerful Pokémon before they destroy the city?