While Ash and Leon's battle in the Masters Eight Tournament finals rages on, Goh and the other Project Mew members are heading for Faraway Island to begin their search for Mew. Aboard the flying research station, Danika apologizes to the junior Chasers for the rushed departure, caused by the sooner-than-anticipated end of the wet season, but also thanks them all for responding to the summons regardless. As they approach Faraway Island, Danika explains that the island is almost perpetually surrounded by storms that make it impossible to approach outside of a small one-week window between the wet and dry seasons. Moreover, turbulent winds prevent their target, Table Mountain, from being approached from the air, so they'll land near the shore and make their way to Table Mountain on foot. Professor Amaranth explains that the year prior, they detected extremely strong Psychic energy near the center of Table Mountain, which could be a sign of Mew, which is how the research team got started.
Once the mobile laboratory has landed, Amaranth tells the Chasers to keep in touch with him and sends them out on their mission. When they enter the jungle, Goh activates a sensor device of his own design, which has now been upgraded by Professor Amaranth. He explains that it picks up nearby Psychic energy and transmits it to the lab, where it's compared to the wavelength of the energy produced by Mewtwo, which he encountered a while back on Cero Island and has a wavelength identical to Mew's. Horace is amazed that something Goh built is being used by Project Mew, but Goh says it's just his field of expertise, just like how Danika specializes in molecular biology and geology, and how Quillon is an expert in studying ecosystems where Pokémon live in harsh conditions untouched by humans. Gary asks if they'll attempt to catch Mew if they find it, but Quillon, being his usual stoic self, doesn't respond, so Horace repeats the question to Goh. While unsure how he'd act in the heat of the moment, Goh is still pretty certain that he'd want to catch it. Horace starts pondering the possibility that, like how Trainers choose which Pokémon they want to catch, Pokémon could also be choosing which Trainers they want to be the ones to catch them. While he's not denying the possibility of the idea, Gary calls Horace out for romanticizing and chuckles at Goh's suggestion of Mew having appeared before him because it wants him to be the one to catch it.
The Chasers arrive at a river. While crossing it on a bridge of roots, they're suddenly attacked by a Swampert. To deal with it, Horace sends out a Virizion and has it use Magical Leaf, successfully driving Swampert off. Goh is amazed at Horace having a Legendary Pokémon, with Horace revealing he caught it during his last Trial Mission. Goh excitedly scans Virizion with his Pokédex before the team moves on.
Finally, the Chasers arrive at the foot of Table Mountain. According to Danika and Quillon, not only has it been a source of horror for ancient fishermen, but its topography has also not changed for hundreds of millions of years, with Quillon going as far as referring it to as the center of the world. They're suddenly contacted by Professor Amaranth, who informs them that the sensor has picked up Psychic energy. However, before he can tell more, the transmission is cut off. The group quickly notices that their other electronic devices, such as the sensor, flashlights, Rotom Phones, and even Poké Balls, are no longer functioning either, which they suspect to be Mew's doing. Danika suggests turning back to get better prepared, but Quillon presses them to not waste this opportunity as if Mew is behind it they may not get this close again. Quillon and his Weavile take the lead in climbing the mountainside, with Gary right behind him, followed by Horace and Goh, and Danika coming in last to secure their rear. At first, the climbing goes without much issue, though Goh curses for having always relied on his Pokémon in difficult situations like this. Suddenly, a Skarmory swoops in and snaps the rope from below Gary, leaving Horace, Goh, and Danika unable to climb higher. Grookey notices a nearby ledge, so the three decide to use it as an alternate way to continue towards the center, while Quillon and Gary continue their climb for the summit.
Carefully moving along the ledge, Danika's group comes across a dangerous-looking waterfall, but her Azumarill spots a cave behind it, so they decide to go through it. Simultaneously, Quillon and Gary reach the summit and head towards the center of the mountain. At the center, they discover an unnaturally round hole, which they suspect to have been created by Mew. While they descend into it with the help of hanging vines, Danika discovers a half-eaten Cheri Berry. Examining it with a microscope, she notices a short, fine strand of hair on it, which could originate from Mew, meaning that it must be close by. As such, she takes the Berry along for a DNA analysis later. Horace wonders if Mew will show up to them, considering it doesn't show up to people with evil intentions. Goh is unworried, as they don't have any evil feelings in them. Danika, nevertheless, tells them to stay cautious, as the reports of Mew sightings that Professor Amaranth had gotten from different regions had told how Mew could either be merciful or cruel, depending on the encounter. Unnoticed by the trio, Mew indeed is in the cave as they speak, following them at a short distance behind them.
Meanwhile, Quillon and Gary have entered a lush cave inhabited by Pokémon, some of them even being Fossil Pokémon. When they fail to find Mew in the cave, they decide to explore further, but are attacked by a Kabutops and an Aerodactyl. Quillon quickly defeats them with his Weavile, allowing him and Gary to move on. Danika's group, at their end, runs into a Solrock and a Lunatone. Grookey tries to fight them on its own, but only ends up being narrowly saved from their attacks by Azumarill's Hydro Pump. The smoke cloud created by the collision of attacks allows the group a chance to run away from the wild Pokémon. However, the problems only escalate when a Groudon suddenly drops down before Quillon and Gary, and Danika's group, while trying to make their way around an underground lake, finds themselves facing a Kyogre.