Sage Murdock has always felt different from the other students at his high school in Boston, and being bullied and ostracized has become a way of life he accepts...but at the same time, he worries that the whispers are true and that he is, in fact, mentally abnormal. After a bullying incident at school provokes Sage to violence, his mother and stepfather tell him he is being sent to live with his biological father on Gray Island, a small weather-beaten island off the coast of Maine. There, Sage encounters many strange people who all seem to be hiding something. A single bright spot is Cadi, a free-spirited girl about his own age. Unfortunately, Cadi is a member of a strange cult-like group that lives on the opposite side of Gray Island. Before long, Sage learns that his relationship with Cadi must end or the consequences will be catastrophic.