Be Cool, Scooby-Doo! - Season 2

Fred and the gang are called in to help with a mystery involving a figure from Fred's past Professor Huh? Fred discovers Rose his old childhood friend with whom he learned mystery solving until they had a falling out has also arrived with her gang. The race to see which gang could solve the mystery first is on as the rest of the gang learns there's more to this story than meets the eye and Fred's interest in finding Professor Huh? is as personal as it gets.