Middleton prepares to make wishes on Posner's Comet, but Cassie worries that a wish won't control big changes ahead, specifically when Sam is offered a dream job across the country. Grace prepares for her valedictorian speech, while Nick becomes unexpectedly nostalgic as high school concludes. Abigail plans a trip to Europe to forget about her breakup with Donovan, while Donovan tries to disprove the power of curses and win her back. Meanwhile, Martha struggles to make amends with her nemesis, and Stephanie and Adam are overwhelmed when their food truck is an instant sensation.
A mysterious, darkly beautiful woman named Cassandra Nightingale moves into an old, abandoned house which is reputed to be haunted by its original owner, "The Grey Lady". The small community is divided in their opinion of her: Some want her to stay (especially widowed police chief Jake Russell and his two children), while others want her to leave. Through the course of the story, seemingly magical things happen, and the community attributes these occurrences to her. Everyone begins to wonder if she is really a witch.