At the Cerise Laboratory, Ash and Goh inform Professor Cerise that they've received a research request from Hodge, a Trainer whom they befriended during the Battle Frontier Flute Cup. His uncle's hot springs had dried out, and soon after, an Absol had been spotted nearby. Some of the townspeople, including Hodge's uncle, believe the old superstition about Absol being a bringer of disasters, and thus are blaming it for causing the incident. As such, Ash and Goh are now intending to figure out the true cause behind the situation. Understanding their point, Professor Cerise dispatches his two research fellows to help Hodge out.
Ash and Goh travel to Lavaridge Town in the Hoenn region, where they meet up with Hodge. They notice that the local shops are closed, as all the tourists have disappeared after the hot springs dried out. Hodge brings Ash and Goh to an old stone tablet depicting Absol in the midst of multiple disasters, saying that his ancestors left it here to warn people of the supposed dangers that Absol posed. One event carved on the stone depicts the hot springs drying out, explaining why people are blaming Absol of causing it now too. Hodge brings Ash and Goh to his uncle's inn, where they find him and a group of townspeople preparing to hunt down and capture Absol. Hodge introduces his friends to his uncle, who doesn't seem to believe they can do anything to help. Ash and Goh protest that what they're planning to do to Absol is wrong, and manage to convince Hodge's uncle into giving them two hours to figure out the true cause behind everything before they head out to hunt for Absol.
The investigation begins at the dried-out hot springs. Hodge says that everything started about half a month ago, when his uncle had spotted Absol on the mountain, after which the water had cooled down and then stopped flowing altogether. Goh reads from his Rotom Phone that Lavaridge Town's hot springs originate from Mt. Chimney. Hodge confirms this, saying that ever since Absol showed up, no one has dared to check the source spring up on the mountain out of fear of running into the Disaster Pokémon. Ash and Goh decide to check it out, while Hodge tries to convince his uncle to give up on his hunting idea.
Ash and Goh start climbing up the mountain road, but as they approach their destination, they suddenly find their path blocked by Absol, who starts attacking them. While they avoid being hit by its attacks, said attacks knock over several trees and block off the road, forcing the two Trainers to search for an alternate route. They do so, soon locating the pipes that pump water down the mountain, and follow it to the spring, where they find the area covered in snow and ice. Goh wonders how the water could've frozen, as hot spring water is heated up by underground magma before it surfaces and thus shouldn't be able to freeze despite the cold. Goh calls out his Trapinch and has it use Dig to investigate underground. Trapinch does so, but quickly resurfacers, shuddering from the cold. As Goh recalls Trapinch, he notices that even the earth dug up by it is frozen, meaning that something is definitely wrong.
Suddenly, a cold wind blows past the two, and they notice a Glalie approaching them. It attacks them, and although Pikachu manages to block its Ice Shard with Electroweb, its Blizzard forces them to seek shelter. Goh stops Ash from attacking back, suggesting they follow Glalie as it leaves, as it and its possible friends could be the reason behind the ground freezing. They do so, stealthily following Glalie to a cave, where it reunites with two other Glalie and a Snorunt. Goh theorizes that they froze up the mountain, as it's too hot for them to live on otherwise. Ash suggests that dealing with the Glalie should solve their problem, but before Goh can even attempt to catch them, Absol suddenly shows up and drives them back, allowing the Glalie to get away before running off itself. Ash wonders if Absol is trying to tell them something, and Goh decides to make a phonecall to Hodge.
Goh informs Hodge of what he and Ash have found out and asks him to check out the stone tablet for anything that's currently happening, which he agrees to. As they climb up the mountain, Goh explains to Ash that if the stone carvings depict events that Absol tried to warn people about earlier, maybe they could figure out what's going on. Just then, Hodge calls back and says that he spotted a drawing of hot springs freezing on the stone tablet, as well as an image of the volcano erupting. Using this information and his Rotom Phone, Goh is able to figure out what's going on: 300 years earlier, Glalie wandered up the mountain and the hot springs froze, after which all the ice melted at once, resulting in a phreatic eruption. The same is happening now, which is why Absol stopped them from catching the Glalie.
Just then, they notice a jet of steam venting out from the mountainside, a sign that the eruption is imminent. They rush up the mountain and see a large boulder blocking a hot spring. Goh figures that they can prevent the eruption by breaking the boulder and letting the steam vent out. He calls out his Cinderace and has it attack the boulder with Pyro Ball, but it has no effect. Pikachu's Thunderbolt proves equally ineffective, and a second round of attacks doesn't help much. However, Absol then appears and attacks the boulder as well, managing to crack it. The three Pokémon keep attacking the boulder, cracking it more and more. However, time is running out, so Absol, out of desperation, rams into the boulder, causing it to finally shatter completely. A jet of superheated water erupts out, and Goh flings a Poké Ball at Absol to save it. The Ball hits and catches Absol, saving it from being hurt by the eruption. Cinderace cools the Poké Ball down and passes it to Goh, who lets Absol out. With the eruption averted, Goh thanks Absol for its warning and tells it it's free to go. Absol, however, instead pushes its Poké Ball out of Goh's hand and returns into it, showing that it wants to stay with him, making Goh happy.
Back in Lavaridge Town, Ash, Goh, and Hodge now get to bathe in the newly rejuvenated hot springs. Hodge thanks Ash and Goh for their help and says that they'll take the Glalie, who are bathing in a vat of ice water next to them, to someplace colder, as Mt. Chimney isn't a suitable place for them anyway. Hodge's uncle, meanwhile, is sorry for having blamed Absol for the incident, and expresses his apology by dumping some ice cold water from the Glalie's bath onto himself. He quickly joins the others in the hot spring to recover from the cold, and they enjoy the comfortable bath together, until the time comes for Ash and Goh to return to Vermilion City.