A tree monster called the Gnarled One attacks a hot dog eating contest with Joey Chestnut. But the mystery everyone really wants answered is "Who is the best competitive eater?" Is it Joey, Shaggy or Scooby-Doo?

Shaggy & Scooby do the unexpected, and welcome a visit to a haunted castle in Germany because famous chef Alton Brown will be there.  Brown tells them the story of his ancestor, who created a Frankenstein-like food monster - which is still haunting the castle to this day.