Sam Cohen is the most popular boy in school: he's attractive, he's top in his class, and he's on track to win a full scholarship to any college of his choice. But just when he's on top, his entire world turns upside-down. Suddenly, he can't stay awake in any of his classes. His temper flares out of control at inopportune moments. And without his prestige status of star athlete, his popularity plummets. But the change that has Sam frightened most is something nobody else can even see—his newfound and uncontrollable bloodlust.