Touring Yellowstone National Park, Ben uncovers a plot by LaGrange who wants to dig up an old treasure from below the national park.
The Tennysons arrive at Yellowstone National Park. Max points out that it's as beautiful as he remembers it. He acknowledges that Ben and Gwen aren't always excited about the places they visit, but Ben interrupts him says that they've been researching Yellowstone all morning. Ben states that people on the internet thinks there's treasure under there. Gwen states that theirs a super volcano under the park. The Tennysons arrive and Ben states he feels good about camping. Two women walk by talking about treasure and Ben follows them.
He arrives at a ranger station and spots LaGrange. LaGrange hears something and walks over towards Vin's car. Ben quickly transforms and hides behind his head as Grey Matter.
LaGrange walks into the ranger station and greets his opponents. He hands him a map and tells them how the race is going down. Grey Matter from outside hears about it, an gets excited. Gwen questions what Ben is doing, but Ben tells her to be quiet. Back inside the building, Vin questions how they know that there is treasure is even there. Mel asks who cares, and mocks Vin asking if he's afraid his car can't handle the dirt. Vin yells back at the two Malachi Sisters stating that real racing is in the streets. LaGrange interrupts asking them to save their energy for the race. Outside Gwen states that Ben was right, and their is treasure, and their going to race for it. Ben imagines him getting there first, and he could win the treasure. He imagines he creates Cybear. The illegal racers then walks out of the station, and Ben and Gwen runs and hides. As they drive off, Ben attempts to transform into XLR8, but instead he gets Diamondhead.
The Tennysons drive in the Rustbucket, with max questioning why Ben transformed into Diamondhead while they have to chance illegal racers. The Malachi Sisters starts hitting Dirty Dobs' vehicle. All of the racers, with the exception of LaGrange, eliminates each other. Vin's car flips over, and the rangers chases him down. Max drives through disgusted by the sights of the destroyed park. Ben states that they need to stop LaGrange and his goons. Max gets angered once he hears LaGrange's name, and he speeds up. LaGrange uses his car's missiles to take out Dirty Dob's car. Back in the Rustbucket, Ben transforms into Stinkfly. He takes out the cannons on the Malachi Sitters cars. And he defeats them. Stinkfly asks Max and Gwen to take care of the Malachi Sisters while he goes to handle LaGrange. LaGrange drives happy, but he notices Ben in the sky. LaGrange manages to escape, and Ben times out and falls in the mud.
LaGrange drives up to the cave, looking at his map. Ben arrives tired, and tells him the race isn't over. LaGrange disagrees and activates a button, releasing a miniature vehicle from his car. Ben transforms into Overflow, expecting something better. They both race through the caves. LaGrange throws explosives at LaGrange, and slows Ben down. Ben notices that their in a geyser, and questions who would hide a treasure there. LaGrange gloats, ready to win the treasure, Overflow bumps into him, which causes him to go flying into the geyser. LaGrange dangles off of the edge of some rocks. Overflow notices treasure, and gets distracted. He wishes to take it, but he sacrifices it to save LaGrange.
Overflow flies out of the geyser with LaGrange, and sets him down, for the rangers to get him. Gwen and Max congratulates Ben. Gwen questions if Ben got the treasure, but Ben states that being a hero and saving the day is enough. The treasure then lands in front of them, and excites Ben. However Max states that since the treasure was found on Federal property, it belongs to the government. The rangers state that they can put the money towards the conservation fund. Ben gets disappointed, that he didn't get the treasure. Max states that in a way, he found the real treasure - the beauty of Yellowstone Park. However Ben isn't impressed.
LaGrange: I'm glad to see you all made it -- the Malachi Sisters, Dirty Dobbs, Vin Ethanol. Vin Ethanol: Yo. LaGrange: Everyone take a map. It outlines the details of today's race course. Vin: Yo, but this goes through miles of protected environmental habitats. LaGrange: Of course it does. We will race through the Grand Prismatic Springs, through the geysers and across the mud pots, and finally, into an abandoned cavern...which happens to be the location of the legendary lost treasure of Yellowstone.
LaGrange: Just one more jump and the treasure will be mine! I am the ultimate racing champion! Overflow: Hey, you're Italian, right? How do you say "you're slow" in Italian? LaGrange: Je suis Franais!