Our heroes return to the Driftveil City Gym and Ash once more challenges Gym Leader Clay to a battle. But once again Clay again tells them he’s too busy to accept Ash’s challenge—this time because he has run out of Revival Herbs. Clay makes a deal with Ash: if Ash can bring him some of these amazing medicinal herbs, Clay will accept his challenge. So our heroes set off to the Driftveil Market to find some.
The gang asks their friend Charles for help, to no avail. Then they learn that the only place where Revival Herbs grow is on Milos Island, known as the Island of Legends. Ash, Iris, and Cilan arrive on the island and are told to seek out a guide named Lewis. They travel a great distance to find him, but Lewis sadly tells them that he can’t find any Revival Herbs either...there hasn’t been any rain for a very long time, and all the herbs have dried up.
Lewis and his Gothorita have planned a rainmaking ceremony to appeal to the Legendary Pokémon Landorus, whose presence is said to make the land fertile. But the Legendary Pokémon Tornadus and Thundurus appear instead, and immediately start attacking each other and our heroes! Tornadus and Thundurus had been blocked from returning to Milos Island by two protective obelisks, but we discover what Team Rocket has been up to recently: tampering with the obelisks to make them stop working. Now the two powerful Legendary Pokémon are back, and they’re ready for a fight—and their rage could destroy Milos Island!
Our heroes valiantly attempt to battle Tornadus and Thundurus, but the angry Legendary Pokémon prove too powerful. Lewis remembers that Landorus is said to be the only one who can control Tornadus and Thundurus, but it can only be summoned by a Shrine Maiden. Iris assumes the identity of the Shrine Maiden, and with Gothorita’s help, begins to send her appeal to Landorus. Will she be able to make contact with the Legendary Pokémon and save Milos Island?