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. Only Marnie, a fledgling witch, can thwart the evil scheme.

Lori Madison is a young woman turning 30 who returns to her Colorado hometown and discovers a childhood list of seven things to do before she turned 30, and finds that she has yet to achieve any of them. So, Lori sets out on a frantic, and humorous quest to accomplish them before her 30th birthday just three weeks away.