Animated adventure following Scooby-Doo (voice of Frank Welker) and the Mystery Inc. gang as they head to England to investigate a medieval mystery. After travelling back in time, the gang find themselves transported to Camelot where Shaggy (Matthew Lillard) inadvertently summons an evil sorceress who believes she is the kingdom's rightful ruler. With the help of King Arthur Pendragon (Jason Isaacs) and wizard Merlin (Nick Frost), the gang set off on a quest to save their friend and the medieval kingdom.