Riley Madison is a Shifter, one of the human population born with the ability to transform into the animal they most closely resemble: their spirit animal. Knowing your spirit animal means knowing what kind of person you are. Most Shifters identify their spirit animal by their teens. Riley is approaching seventeen and still doesn’t know hers: a fact that’s beginning to worry her.She befriends Tristan Dawes, another Shifter in the same situation, and quickly finds their fates are connected when she sees an outline of a star in his eyes. A man named Christopher has a master plan for the three Shifters marked by the stars in their eyes. He needs them to identify their spirit animals in order to bring about his life’s work, and is willing to do whatever it takes to make them. At first he tries subtlety. When that fails, he targets Riley’s family.As Riley grows closer to identifying her spirit animal, her mother receives a cryptic phone call and disappears to find her father. The Shifters draw closer to war with Elementalists (humans with the ability to control one of the elements) and Riley finds herself fighting for the first time in her life – against Elementalists, Shifters, and even her own family.