Orphaned and deeply saddened, Cassie Blake moves in with her warm and loving grandmother Jane in the beautiful small town of Chance Harbor, Washington where the residents seem to know more about Cassie than she does about herself. As Cassie gets to know her high school classmates, strange and frightening things begin to happen. When her new friends explain that they are all descended from powerful witches, and they've been waiting for Cassie to join them and complete a new generation of the Secret Circle.