Digital Magic by Philippa Ballantine

Penherem is a quaint, sleepy English village where people go to escape the 21st Century. Hiding from the world of laptop computers, the Internet, and wireless communication, is Ella. A writer, now barren of ideas and drive, she resigns herself to a quiet life of solitude. Everything changes with the arrival of a shapeshifting thief. Suddenly, everyone begins to change–from the local librarian to the lady of the manor–revealing their true natures and dangerous secrets. Something in this sleepy English village is awakening… something that might be better left alone.