Evelyn will be sixteen forever, but William will live a long, happy life, if Evelyn has anything to do with it. As William’s Shadow, it’s her job to watch over and to protect him. Trouble is, William likes to push limits and test boundaries, which makes Evelyn’s job a difficult one. Evelyn thought her choice to become a Shadow was the toughest thing she had ever done; that is, until she crossed the forbidden boundary and fell in love with her "living one”, William. Her mentor warned her that only heartache can come from loving a living one but Evelyn can’t help herself. When William is gravely injured, he is taken to the Light where is able to see Evelyn for the first time and when he does, he realizes that she is the girl he’s been waiting for his whole life. He falls instantly and profoundly in love with her. Meanwhile, the Darkness has declared war against the Light, trying to claim as many souls as possible. Now, the pair must figure out a way to be together, while forces of Light and Darkness battle for William’s soul.