The legendary gumiho or nine-tailed fox, Goo San Duk, leaves her husband after his betrayal renders her unable to shapeshift. She takes her nine-year-old daughter, Yeon Yi, who has yet to gain the ability to use her gumiho powers, to a village in order to protect her. As Yeon Yi turns ten, her physical transformation begins, putting her in increasing danger of being discovered by her neighbors.