Daughters of the Sea #1: Hannah by Kathryn Lasky (Published by Scholastic, September 1, 2009)
Daughters of the Sea tells the story of 3 mermaid sisters who are separated at birth by a storm and go on to lead three very different lives. Book 1 is about Hannah, who spent her early days in an orphanage and is now a scullery maid in the house of rich, powerful family. She is irresistibly drawn to the sea and through a series of accidents and encounters discovers her true identity. Hannah relizes that she must keep the truth a secret but she also knows that soon she will have to make the choice - to be a creature of the land or the sea.
Kathryn Lasky wrote many books in the Royal Diaries and Dear America series that I loved. This sounds like it will be a really interesting and enjoyable blend of historical fiction and fantasy. I can't wait to read it!