Scooby-Doo and his pals win an all-expense paid vacation and embark on a trip of a lifetime to a tropical paradise. Their destination however, turns out to be Zombie Island. As soon as they arrive, they realize the place looks strangely familiar and is reminiscent of a trip they took years ago, in which they became wrapped up in a mystery involving zombies. The gang soon learns that their trip to paradise comes with a price when the zombies re-emerge and attack their hotel. Will Scooby-Doo and the Mystery Inc. gang finally solve the mystery behind Zombie Island?

The Joker is aided in his Halloween quest to render modern technology useless and take over Gotham City by Solomon Grundy, Silver Banshee, Clayface and Scarecrow.