On Iron Island, Ash's rival Barry is training with his Empoleon and Heracross when Empoleon suddenly turns on its Trainer. Barry calls Ash and Dawn, who are still in Canalave Town, to tell them what happened—other Pokémon on Iron Island are acting strangely, too! Ash and his friends catch the next ferry to Iron Island, with Team Rocket following them in secret, but Barry has already gone out to explore the island. Whatever is happening, only Steel-type Pokémon are affected, but why?

Ash and his friends search for Barry and encounter more Steel-type Pokémon running amok. Ash is even saved from an angry Aggron by a dapper Trainer, Riley, and his Lucario. Riley is a Steel-type Trainer who lives on Iron Island, and his Lucario uses its Aura to protect itself from the low-frequency wave that's driving other Steel-type Pokémon mad. Barry and his Heracross, off on their own investigation, spot a strange machine. Barry runs into Team Rocket and promptly blames them for everything, but Team Rocket denies that the machine is theirs. Barry and Team Rocket go to get a closer look, and discover that the machine is part of a Team Galactic operation headed up by Commander Mars!

When Team Galactic spots them, Barry and Team Rocket put up a fight but are quickly overpowered and knocked into an ancient underground ruin. Up on the surface, Riley and our heroes have also tracked Team Galactic to the ruins, which are made of metal. Together with Team Galactic's Spear Key, this must be causing the low-frequency wave! Commander Mars releases the Spear Key and the Key melds with the ruins, which release a huge bolt of energy. The wave of energy knocks Lucario backwards; as it gets to its feet, it's overcome by a strange power and prepares to attack!