Ben meets an alien con artist named Professor Blarney T. Hokestar whose miracle elixir is extracted from a small alien called a Screegit that is kept in his lab. When a Florauna activist named Pax convinces Ben to help him free the small alien from Hokestar's lab, chaos ensues when the nitrogen in Earth's atmosphere turns the exposed Screegit into a giant, acid-spitting monster with Ben having to keep it from wrecking the city.