Scooby-Doo and the gang team up with their pals, Bill Nye The Science Guy and Elvira Mistress of the Dark, to solve this mystery of gigantic proportions and save Crystal Cove!
Mystery Inc. withdraws from solving crimes after botching a case. When Vincent Van Ghoul contacts the gang about an unfinished investigation from Daphne, Shaggy and Scooby's past, the gang springs into action to finish the job that involves catching the 13th Ghost that escaped from the Chest of Demons and is still at large.
On Halloween night, two precocious little girls try to save their parents from their nasty old capitalist aunt's greedy clutches. Magic abounds and they meet mysterious new friends along the way.
In Los Angeles, on Halloween night, a hitman tries to transport a corpse in plain sight, but people he stumbles upon on the street, believing that his sophisticated appearance is a magnificent disguise, constantly stand in his way to congratulate him.