Emily Webb is a Geek--and happy that way. She's never been the kind of girl who sneaks out for parties. And she definitely doesn't start fights or flirt with other girls' boyfriends. Until one night Emily finds herself doing exactly that . . . the same night a classmate--also named Emily--is found mysteriously murdered.

Thing is, Emily doesn't know why she's doing this. Every night she gets wilder until it's no longer just her personality that changes; she's also becoming strong, and fast, and utterly fearless. Has she been bewitched by the soul of the other, murdered Emily? Or is Emily Webb becoming something else entirely--something not human?