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.

After Scott has a fight with his father and runs away and when his father refuses to go after him. His mother, Collette, then goes to one of her former boyfriends, Jack, a lawyer, and tells him that he’s her son’s real father. Jack initially refuses. So she goes to another boyfriend, Dale, who goes off looking for Scott. Eventually the two men meet and realize that they are looking for the same boy and that Collette told them they are the boy’s father. What follows is a mad chase, cause the boy doesn’t want to go back.