Burch opens her YA paranormal series with a chomp: “Fangs settled into Nikki Youngblood’s leg.” After that in media bite of an opener, readers quickly learn about three halflings—half-angels, half-humans, who look like teenage boys—sent to protect 17-year-old Nikki. Mace, Raven, and Vine live with their angel “father” and crew chief, Will. Something odd is going on in Nikki’s small Missouri town, and it involves a local lab, her biology teacher, and, possibly, her godfather. Complicating emotional matters is the attraction Nikki feels to both Mace and Raven, which is mutual with each boy and also forbidden. Burch has a great idea, and details about the halflings intrigue: they generate an electrical field, and varied powers are “perks” of their half-divine birthright. The book has some technical problems. Nikki’s parents aren’t well-developed and their presence is fairly arbitrary; the villain has the subtlety of an elbow to the ribs; and the writing is too often trite (“fear and torment had stolen the last shreds of her strength”). Still, this is popcorn: easy to overlook flaws, gobble up, and seek more. Ages 15–up. (Feb.)