Guardian of the Gate (Prophecy of the Sisters Trilogy)
"Michelle  Zink lives in New York with her four children. Prophecy of the Sisters  was her first novel and was chosen as one of Booklists Top Ten Debut  Novels of 2009 and as one of the Chicago Public Library's Best Books for  Young Readers. It has also been listed on the New York Public Library's  Stuff for the Teen Age and the Lone Star Reading List."