Like most sixteen-year-old girls, Cassie O'Connell wonders what it's like to be in love. For Cassie, that question is even more daunting as ten years ago a virus wiped out every male on the planet. Well, almost every male. Cassie discovers two teenage boys, one who has been locked away in a secret isolation chamber. The other boy is immune to the virus. He seeks revenge against the psychotic "man" who is responsible for the murder of his mother and sister. Will the boy's thirst for vengeance endanger Cassie's life as well as his own? As she struggles with her feelings for both boys, Cassie is propelled towards a destiny that will change the world forever.