Lake Valor is the site of the Grand Festival, and the next stop for Ash and the gang. But on the way, they meet a Pokémon Ranger named Ben, who’s trying his hardest to capture a rare Heatran. The members of Team Rocket want in on the action, too, and vow to catch Heatran for themselves. Shortly after all the commotion, Ben is found. He has crashed into a river, only to be rescued by a Feraligatr.
Ben asks our heroes for help in capturing Heatran. They agree, and they all set off in anxious search of the special Pokémon. But soon after they discover Heatran in a lava-filled cave, the cave begins to crumble, compelling Ben, Ash, and the gang to jump into action! When the Team Rocket baddies realize they are in over their heads, they hightail it out of the cave. After moves from Piplup, Buneary, and Buizel cool down the lava, a final Ice Beam from Feraligatr chills the lava enough for Ben to rescue Heatran and begin transporting it to the National Park.
Thanking our heroes for their assistance, Ben and Heatran board a helicopter for their destination, and once again the journey toward Lake Valor and the Grand Festival continues!
Looking into a volcanic crater, Pokémon Ranger Ben is trying to capture a Heatran that knows Eruption. Just before he can capture it, a small earthquake takes place, making Heatran flee. Ben then captures a passing Pidgeot and uses it to chase after Heatran. However, as he finds Heatran, so does Team Rocket, who uses their RoboDiglett to break some boulders in order to stop Heatran in its tracks. Heatran quickly escapes, though Pidgeot gets struck instead, leading Ben to plummet into the river below. Using a Ranger Sign, he calls upon a Feraligatr to rescue him and take him downstream, which it successfully does.
Ben and Feraligatr take a dive down a waterfall, and the resulting splash alerts Ash and his friends, who are preparing lunch nearby. They rush over to the river, where Feraligatr tosses Ben onto the rocky banks. Ben makes a swift recovery and introduces himself as a Pokémon Ranger. He then panics after noticing that his Capture Styler is missing. Ben asks the group if they have seen Heatran, explaining to them that the Heatran he's looking for is special, as it can use Eruption, which a normal Heatran is unable to learn. He plans to take it to a National Park and requests the group's help, to which they gladly agree. Meanwhile, Team Rocket locates Ben's Capture Styler downstream and plans to use it to capture Heatran for Giovanni.
Ben leads Ash and his friends up a mountain in his search for Heatran. He pauses to feel the ground several times to check the temperature for warmth, as Heatran only live near volcanoes. The field technique leads them directly to a cave where the ground is especially warm. Without them noticing, Team Rocket also follows them inside. As the group ventures deeper, they spot a lake of magma and Heatran, whose Flash Fire Ability is absorbing the heat from below. Ben is frustrated as he doesn’t have his Styler on him, and he cannot use a Poké Ball to complete his mission.
Team Rocket appears again with their RoboDiglett and recites their motto. James then tries to use the Capture Styler, but fails. Ben explains that he's the only one who can use it. Meowth uses the RoboDiglett to try to capture Heatran with a net, but Heatran stops it with Eruption. However, the blow causes some of the cavern wall to collapse. Sensing Heatran is in trouble, Ben bravely heads down towards the magma, and he is already beginning to suffer pain from the intense conditions. Brock suggests they cool things down, so Ash and Dawn send out Buizel, Piplup, and Buneary for the task. Ben takes the Capture Styler back from James, but the floor under him crumbles and he almost falls into the magma below. Pikachu uses Thunderbolt on Team Rocket, causing Meowth to drop the RoboDiglett remote into the lava, causing the mecha to go out of control. Heatran subsequently destroys the RoboDiglett with Eruption. When Heatran is about to fall into the magma, Ben summons Feraligatr to use Ice Beam on it, solidifying it. Thanks to this, Heatran survives the fall mostly unscathed. As more rocks descend, Team Rocket promptly exists the cave to safety.
Ash and Dawn quickly recall their Pokémon, and order Ben to get out. Ben pleads with Heatran to listen to him and reassures it of its safety. Using his Capture Styler, Ben soon captures it. After making a successful escape, Ben contacts his waiting helicopter to be picked up. Ben thanks the group for their help before leaving to escort Heatran to the National Park.