Ariella Montero's mother vanished the day she was born, leaving her to the care of her overprotective scientist father, who homeschools her and limits her contact with the outside world. Only when she reaches adolescence does Ari discover that her special diet and insular home life set her apart from her peers. Her father's confession that he was vampirized shortly before marriage, and that Ari can choose whether to be undead like him or mortal like her mom, set her off on a road trip that eventually brings her to her mother and into an understanding of tough truths about her family.