When Dewi is clobbered by a falling rat, the nosy Welsh dragon snoops his way into a challenging predicament. Helped by a toad with a passion for chemical wart cures, Dewi discovers that a megalomaniac baron is secretly breeding mutant corn at an unfriendly castle. To thwart the genetically modified-corn baron's sickening plan, he must use moxie and firepower in a series of catastrophe-skirting capers.