The perpetually inept hillbilly Ernest P. Worrell (Jim Varney) is working as a janitor at a university when he accidentally stumbles across an antique plate, which the school's history professor, Dr. Abner Melon (Ron K. James), believes may lead to the long missing "real" Crown Jewels of England. As the unlikely allies Ernest and Melon begin their search, they wind up attracting the attention of Scotland Yard, whose detectives are eager to find the jewels before Ernest can.