Marnie Piper prepares to begin a new school year, she asks the Halloweentown Hot Witches’ Council to work toward openness between Halloweentown and the mortal world. She proposes to bring a group of Halloweentown students to her own high school in the mortal world.

The Cromwell clan live in the real world, except for their grandmother who lives in Halloweentown, a place where monsters go to escape reality. But now the son of the Cromwells’ old enemy Kalabar has a plan to use the grandmother’s book to turn Halloweentown into a grey dreary version of the real world, while transform the denizens of the real world into monsters.

On her 13th birthday, Marnie learns she’s a witch, discovers a secret portal, and is transported to Halloweentown — a magical place where ghosts and ghouls, witches and werewolves live apart from the human world. But she soon finds herself battling wicked warlocks, evil curses, and endless surprises.