Ben, Gwen, and Grandpa Max are in a vacation at Yellowstone Park, where they find strange happenings. Ben finds a new form, Cannon Bolt, an alien capable of rolling up much like an armadillo. At first, Ben wasn't fond of his newfound form very much, but later, he must put what he has in good use. Suddenly, a large tick-looking alien from space lands on the surface of the Earth, causing great havoc and danger. Three aliens soon after appear, who claim themselves to be worshippers of the giant alien. They refer to it as The Great One, and it has the ability to absorb the life out of a planet, until it can no longer support itself. Will Ben find a way to stop the big tick, and see what this new alien form can do?
