Sam Maddox, a troubled girl whose father committed suicide, has earned a reputation at her high school for being a bit promiscuous. When Sam begins seeing brilliant, MIT-bound Henry Sinclair, the two opposites really attract. Although Sam doesn't realize it, Henry is in the grip of an insane romantic obsession, and he will kill anyone who tries to put an end to his star-crossed - and increasingly deadly - romance.

Aubrey Fleming is a regular high school student with friends and family. One night, she unexpectedly disappears. Two weeks later she is found unconscious in the middle of the woods. When spoken to, her loved ones realize she has forgotten her identity and the personality living in her body is Dakota Moss, a character that Aubrey created in one of her stories for an English assignment. Dakota denies ever being Aubrey knowing that they look identical. Now, Dakota must try to unravel the mystery of how her and Aubrey co-exist and find out who abducted Aubrey that night.