The Unwanted — John Saul

Cassie Winslow is sixteen.  She has just lost her mother in a terrible accident.  Now, lonely and frightened, she has come to live with the father she barely knows and his new family in tiny False Harbor on Cape Cod.  For Cassie, the strange, unsettling dreams that come to her suddenly in the dead of night are merely the beginning.  Very soon, Cassie Winslow will come to know the terrifying powers that are her gift.  And in the village of False Harbor, nothing will ever be the same.