Mystic by Alyson Noel
After experiencing terrifying visions, Daire Santos goes to live with her grandmother in the dusty New Mexico town of Enchantment. There she discovers that she's a Soul Seeker - a person who can navigate between the living and the dead. Guided by her grandmother, Daire has learned how to harness her powers - just in time. Enchantment is controlled by the evil Richter family, who are determined to rule over the Lowerworld, Middleworld and Upperworld - upsetting the natural balance and causing chaos. Daire is the only person who can stop the Richters, but there's one problem: she's in love with Dace, whose twin brother Cade is a shape-shifter, out to steal Daire's powers. And both boys belong to the Richter clan. Can Daire fulfil her destiny without destroying her one true love?