Selene Rhodes has lived her whole life with a terrible secret: not only can she take the form of any animal at will, but once a month the full moon transforms her into a fierce wolf-creature without a human conscience. Managing her condition means living by a strict routine, and more importantly, abstaining from intimate relationships with human beings. Selene is convinced that love and friendship can only bring her pain.

Forensic pathologist Eve Thomas is well-acquainted with the pain of romantic love. Swearing off relationships after having her heart broken by a cheating ex, Eve throws herself into her work: catching murderers. When Selene comes to her aid after an attack by a masked man in Golden Gate Park, Eve is shocked by how powerfully she is drawn to her mysterious savior.

Shaken by her own feelings for Eve, Selene is even more terrified to realize she isn't even close to being the scariest monster stalking San Francisco. There is someone out in the city who is killing for pleasure, and his next target is the one woman he thinks might be able to stop him: Eve