The Energy Plant in Galar has suffered damage after too many Galar Particles were absorbed by its core. Macro Cosmos Chairman Rose informs his secretary Oleana of the emergency. As she orders urgent repairs be done on the hangar, the Galar Particles disperse into the air. Rose simply smiles, marvelling as the mysterious energy streaks across the night sky.
Meanwhile at the Cerise Laboratory, a mysterious reddish glow appears inside Ash's bag, coming from his Dynamax Band. Consulting Professor Cerise, Ash and Goh learn that Dynamax Bands are used by Trainers from the Galar region to Dynamax and Gigantamax their Pokémon. Goh recalls his previous encounters with the peculiar phenomena, adding that it is strange that Pokémon can only undergo Dynamax in either stadiums or the Wild Area. Chrysa and Ren add that recent reports have shown Dynamax occurring right across the Galar region. Ash wonders if his Dynamax Band glowing is at all related, to which Goh suggests they go on an investigative trip to Galar. The Professor agrees, sending the boys on a plane to Galar.
Aboard a train to Wedgehurst to meet Professor Cerise's friend Professor Magnolia, Ash and Pikachu indulge in some Galar scones. The train ride comes to an unexpected stop due to some thick fog, and the train doors open to allow the passengers to stretch their legs while they wait. Goh's disappointment quickly subsides when a hungry Bunnelby tries to steal some scones. The boys run into the Slumbering Weald after Bunnelby, quickly losing sight of their target. Goh then spots it hopping by and manages to catch the Bunnelby, though he has become separated from Ash. While searching for Goh, Ash and Pikachu encounter Zacian. Ash tries to scan it with his Rotom Phone, however the Legendary Pokémon isn't registered in the Pokédex database. Similarly, Goh has a mysterious encounter of his own, meeting Zamazenta. Ash tries to battle Zacian, but Pikachu's Iron Tail goes through it. Goh, meanwhile tries to catch Zamazenta for himself, but the Poké Ball goes through as well. Goh has Raboot try an Ember attack, but it doesn't affect Zamazenta. Both Zacian and Zamazenta let out a haunting howl, enveloping the area in a thicker fog. Goh wakes up to find himself alone in the Slumbering Weald and Ash is still nowhere to be seen. He tries calling him on the Rotom Phone, but Ash doesn’t answer. The train horn sounds, so Goh and his Pokémon rush for it, only to miss the now departing train.
Next, Goh spots several streaking stars across the sky, noting they look a lot like the ones seen when a Pokémon Dynamaxes. A car suddenly pulls up, and a familiar face, Sonia takes a moment to observe the strange stars. She then turns to see Goh standing there, much to her surprise. Ash and Pikachu wake up in the Slumbering Weald, and as they decide to head back for the train to meet Goh, they also spot the mysterious stars in the sky.
In a small town, one of the stars strikes Centy, a Centiskorch belonging to father and daughter Doug and Eva. Centy undergoes a fearsome transformation into a Gigantamax Centiskorch before destroying a building with a G-Max Centiferno. The news of Dynamax sightings across Galar has also reached Oleana and Rose, however Rose is undeterred, noting that a few casualties are inevitable and that the future must be the main priority.
Ash runs into town, perplexed by the sight of a Gigantamax Centiskorch outside a stadium or the Wild Area. He decides to confront it himself, ignoring Doug's advice to stay safe. Ash orders Pikachu and his Riolu to help calm Centy down. An Electroweb wraps around Centy's face before Riolu scores a direct hit with Vacuum Wave. Centy, however, breaks through the web and prepares to launch a Max Flutterby. Ash adds Dragonite to the battle for a triple combo of Hurricane alongside Pikachu's Electroweb and Riolu using Vacuum Wave again. The attacks cancel each other out while the Gigantamax Centiskorch still stands. Centiskorch prepares to unleash another devastating G-Max Centiferno, leading Ash and his team to scramble to safety. Champion Leon and his Charizard fly onto the scene, striking the Gigantamax Centiskorch with a Rock Tomb. Ash is glad to see some support arrive, and Leon decides to handle the situation by himself. A final blow of Air Slash reverts Centy to its previously friendly self and ends the chaos. Eva rushes to hug her dear friend, while Doug thanks Ash for helping save Centy. The unexpected arrival of Leon also receives much praise from the townspeople. Leon stays humble and proclaims that he will be investigating the recent rise in Dynamax Pokémon. As he prepares to leave to fight other Dynamax events, Ash pleads with the Champion to let him help. The glint of confidence convinces Leon to relent, so Ash aboards his Dragonite and follows Leon and Charizard to the next battle.
Thanks to Sonia, Goh is also making progress. Goh then remembers to give Ash another call, and this time Ash picks up. Ash reveals that so much has happened and that he is now assisting Leon with defeating the Dynamax Pokémon. Goh replies that he and Sonia are traveling to the Turffield geoglyph, hoping that it might be somehow connected to the outbreak of Dynamax energy across Galar. Goh tells Ash that they will meet up when they can. As a dark red cloud appears overhead, Ash hangs up the phone as he and Leon prepare to take on their next opponent – a Dynamax Pangoro.