As a child, Olivia Dunham is "Subject 13," exposed to the experimental drug Cortexiphan. The effects it has upon her manifest when her stepfather assaults her mother—with dire consequences. All of her life, Olivia hides the strange things Cortexiphan has done to her. But when faced with a life-or-death situation, she can no longer deny her true nature. For if she does, someone close to her will die.