Cassie Blake's (Britt Robertson, "Life Unexpected") world is turned upside down after her mother dies in a mysterious accident, forcing Cassie to move in with her loving grandmother Jane (Ashley Crow, "Heroes") in the small town of Chance Harbor, Washington. While trying to adjust to her new life, Cassie is quickly befriended by Diana Meade (Shelley Hennig, "Days of Our Lives"), a sweet-natured classmate who offers to show her around and introduces her to mean-girl Faye (Phoebe Tonkin, "H2O: Just Add Water"), her sidekick Melissa (Jessica Parker Kennedy, "50/50," "Smallville") and Cassie's next door neighbor Nick (Louis Hunter, "Out of the Blue"). Things get complicated when she meets Adam (Thomas Dekker, "Terminator: The Sarah Connor Chronicles"), Diana's boyfriend, with whom she feels an instant and powerful connection. Upon meeting one of her mother's childhood friends, Dawn Chamberlain (Natasha Henstridge, "Species"), the school principal and Faye's mother, Cassie begins to wonder why her mother never spoke of her hometown. When strange and dangerous things begin to happen, Cassie's new friends are forced to tell her their secret - they are all witches and her arrival will complete the Circle. However, the Circle has not been drawn together again by chance - Diana's father, Charles Meade (Gale Harold, "Queer as Folk," "Desperate Housewives") has plans of his own for the group.