Outside Dragonspiral Tower, Ash, Cilan, and Iris meet Professor Cedric Juniper’s assistant Nick, who offers them a ride to meet the professor at the White Ruins. En route, he tells them the excavation team may have made a fantastic discovery, but won’t say any more.
Inside the ruins, our heroes are reunited with Cedric, who shows them a door covered in mysterious symbols. He moves a few panels around, and the door comes open! There, in front of their awestruck eyes, is the Light Stone—an item straight out of legend that is said to be Reshiram in a different form! The professor picks up the stone, and it bursts into flame in his hands, sending a bright blast of light straight up into the air and leaving him unharmed.
From a distance, N sees the light and senses Reshiram’s presence. He makes his way to the ruins, surprising Professor Juniper and the others, and demands to know what the professor plans to do with the stone. Cedric explains that the Light Stone and Reshiram are part of his life’s work, and says he plans to investigate the stone thoroughly. N finds this unacceptable and leaps into action, grabbing the case with the stone in it and running away. Ash chases after him, but the ground gives way under his feet. N goes back to help him—even dropping the case to grab Ash’s hand—but finds himself falling as well, and the two of them land on soft sand deep underground.
Back on the surface, the others are trying to figure out how to get Ash and N out when they get some unexpected visitors: Team Plasma! The villains also saw the blast of light from the stone and followed it to the ruins, planning to get their hands on both N and the Light Stone. They’re prepared to attack Iris, Cilan, and Cedric when Nick reveals his true identity: it’s Looker, from the International Police! He corners Team Plasma’s Aldith and says reinforcements are on their way, but Colress activates his now perfected machine and takes control of the Golurk who have been helping with the excavation, turning them against our heroes!
Jessie, James, and Meowth have tracked Team Plasma to the site, but they decide to sit back and wait for the dust to settle before leaping in to steal the Light Stone and Pikachu. Underground, N and Ash are having an intense conversation about the relationships between people and Pokémon. N still thinks Pokémon would be better off without people, but Ash insists that he just wants to learn more about Pokémon and be really good friends with them—including Reshiram!
Then the two hear the sounds of battle above them and decide they have to find a way out. Who will claim the Light Stone when this battle is over?