Scooby-Doo and the Mystery Gang visit Oakhaven, Massachusetts to seek strange goings on involving a famous horror novelist and his ancestor who is rumored to have been a witch.
When a man claiming to be long-lost Uncle Fester reappears after 25 years lost, the family plans a celebration to wake the dead. But the kids barely have time to warm up the electric chair before Morticia begins to suspect Fester is fraud when he can't recall any of the details of Fester's life.
After a family tragedy, three generations of the Deetz family return home to Winter River. Still haunted by Betelgeuse, Lydia's life is turned upside down when her teenage daughter, Astrid, accidentally opens the portal to the Afterlife.
Marnie puts her magic on the line to get several Halloweentown teenagers transferred to her high school in the mortal world. But soon, Marnie and her new friends are in trouble and out of luck when the evil Knight Of The Iron Dagger appears. He's determined to destroy all things magical, and it's up to Marnie to save her high school, the human world and her magic.