Aunt Jenny is set to compete in the annual Greenville go-kart race. With help from Riley, Theo, Alex, and Beatrix, they put together the "Megablaster", an elite go-kart with a great chance at winning. When Kaboom hears about the prize and glory that comes with winning the race, he decides to build his own go-kart - by taking vehicle parts and items from all over town. Megablast transforms into Rocket, Thunder, and Metallix to do damage control.