Sabrina and her cat, Salem, travel to Colonial-era Westbridge to research a history project, but Sabrina's powers have been time-locked so that she won't change history. Their first shock is meeting Harvard Kinklin and Libbeth Chestler--dead ringers for Harvey and Libby. Libbeth is as jealous as her alter ego; when she sees Sabrina talking to her cat, she brings charges of witchcraft against them. Suddenly Sabrina and Salem are trapped in the past with only their wits to escape and time is running out.