The Secret of Moonacre

When 13 year old Maria Merryweather's father dies, leaving her orphaned and homeless, she is forced to leave her luxurious London life to go and live with Sir Benjamin, an eccentric uncle she didn't know she had, at the mysterious Moonacre Manor. Soon Maria finds herself in a crumbling moonlit world torn apart by the hatred of an ancient feud with the dark and sinister De Noir family. Maria discovers that she is the last Moon Princess and, guided by an unlikely mix of allies, she must overcome her family's pride in order to unearth the secrets of the past before the 5000th moon rises and Moonacre disappears into the sea forever. (via imdb.com)