Twin sisters Dorothy and Constance live on a small island off the Scottish coast.  In the midst of the war, five hundred Italian soldiers are sent to the island to work in the prison camp.  Told in multiple viewpoints, The Metal Heart follows both sisters and one of the prisoners.

I highly recommend the audiobook of The Metal Heart.  The narrators do a phenomenal job!  The ending is absolutely heartbreaking and there is a twist I didn't see coming!