The Mystery Inc. gang have gone their separate ways and have been apart for two years, until they each receive an invitation to Spooky Island. Not knowing that the others have also been invited, they show up and discover an amusement park that affects young visitors in very strange ways.
When foreman Frank shows new employee Freddy a secret military experiment in a supply warehouse in Louisville, Kentucky, the two klutzes accidentally release a gas that reanimates corpses into flesh-eating zombies. As the epidemic spreads throughout the town, and the creatures satisfy their hunger in gory and outlandish ways, Frank and Freddy fight to survive with the help of their boss and a mysterious mortician.
