Ash and his friends are preparing a meal by a river. Meanwhile further upstream a Pokémon Ranger named Ben is trying to capture a Heatran which knows Eruption. Just before he could capture it, a small earthquake takes place making Heatran flee. Ben then catches a Pidgeot which is flying by and he uses to chase after Heatran. However as he finds Heatran so does Team Rocket who use their RoboDiglett to break the boulders in order to stop Heatran in its tracks. It quickly escapes and one of the boulders hits Pidgeot and sends Ben plummeting into the river. He then calls upon a Feraligatr to rescue him and take him downstream, which Feraligatr successfully does.
Ben then floats down the river to Ash, Brock and Dawn and introduces himself as a Pokémon Ranger. As he is talking with them he notices his Capture Styler is missing. He then asks them if they have spotted Heatran. Ben explains to them that it is a special one as it is the only one of its kind which can learn Eruption. He plans to take it to the National Park. Then he requests their help to which they gladly agree.
Meanwhile as Team Rocket is walking down the stream they find Ben's Capture Styler and plan to use it to capture Heatran. Meowth then has a fantasy of the boss using Heatran as a grill, a sauna heater and a fireplace.
Ben, Ash, Dawn, and Brock are climbing up a mountain. Ben then checks the temperature of the ground to feel if there are any volcanoes nearby. They keep going as Ben constantly checks the temperature which is getting warmer and warmer. They then approach a cave where the ground is especially warm due to the flow of magma and go inside it. Team Rocket then appears and follows them inside. As the group goes deeper inside the cave they find a lake of lava where they spot Heatran whose Ability Flash Fire activates.
Team Rocket appears again with their RoboDiglett and recite their motto. Then, James tries to use the Capture Styler but fails. Ben then says he's the only one who can use it. Meowth uses the RoboDiglett to try to capture Heatran, but Heatran stops it with Eruption. The cave wall is about to collapse and Heatran is in trouble. Ben bravely goes and helps Heatran, Ash and Dawn help him by cooling down the floor with their Pokémon. Ben takes the Capture Styler from James, but the floor under him crumbles and he almost falls into the lava. Pikachu then uses Thunderbolt on Team Rocket and Meowth drops the RoboDiglett remote into the lava. Heatran then destroys the RoboDigglet with Eruption.
Heatran is holding on to a rock that is falling into the lava, Ben then summons Feraligatr who uses Ice Beam on the lava. Heatran is saved then Ben captures it and they escape the cave as it collapses. Outside, Ben asks for a helicopter using his Styler to come by and pick him and Heatran up. He then shakes hands with Ash while the helicopter arrives. As the helicopter is leaving, he bids farewell to the group.
The scene cuts with the narrator's conclusion.