The Mega Mondo Pop Cartoon-a-Con in sunny California marks the spot for mystery. Some celebrated comic book characters are headlining at the unconventional convention and megabucks movie premiere. When the gruesome villain Mr. Hyde unleashes monster bats, howling hounds and sinister slime upon the festivities, the super powered tag team of Shaggy and Scooby-Doo tap into their inner super heroes to prevent the entire event from being smothered in ghoulish green goo.