Casey Shield, a hacker who invented the Dynamax Simulator, and Henry Sword, a boy who repairs gear for Pokémon, both dream of entering the Galar region's Gym battles. For Casey, it's a chance to reunite with her lost Pokémon. For Henry, it's an opportunity to search for the legendary Rusted Sword and Rusted Shield.

As Henry and Opal's battle wages on in Ballonlea, Gym Leader Raihan infiltrates the Hammerlocke Energy Plant to investigate a strange occurrence there. Then, Casey must battle Opal for her own Gym challenge.

Is there really a Dynamaxed Pokémon in the Route 9 Tunnel?!