Feeling gypped at a boring mid-west tourist attraction, Ben's payback ruins several exhibitions. One exhibit, though, turns out to be a lot more than anyone bargained for when it releases a relentless electrical prankster named Megawatt.
Ben is too short for a ride at a water park, so he uses the Omnitrix to sneak in. An alien enthusiast captures Grey Matter and wants to announce it to the world, so he contacts The Organization, which wants the alien for its own plans.
Ben's cold affects his alien transformations, leaving Wildbeast virtually blind, Four Arms with putrid puss pockets and Heatblast far from able to warm up. Not good when there's a bug-manipulating maniac threatening a city.
Vilgax himself finally comes after Ben. As Ben finds Vilgax to be more than he and his alien selves can handle, Grandpa Max reveals a secret past when he seeks help from a hidden base beneath Mount Rushmore.