Scooby-Doo and his friends are drawn to a strange object in the middle of Nowhere, Kansas--the backwoods hometown of Courage and his owners, Eustace and Muriel Bagge.

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?

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.