Palace of Mirrors, by Margaret Peterson Haddix
Margaret Peterson Haddix is no stranger to princess stories. In Just Ella, Ella Brown discovers that being a princess is not all that it is cracked up to be. In Palace of Mirrors, Cecilia is a different kind of princess. Raised in a remote village, in a simple household, she has been told that she is the true princess, who must be hidden to keep her safe. By day she is responsible for the chores that all village girls take on, while at night she pores over her royal studies. She waits for the day when it is safe for her to return to the palace, where a decoy princess, Desmia, now sits on the throne. But when Cecilia and Desmia meet face to face, they discover that both have been misled, and neither is the person she thought she was. Cecilia, Desmia, Harper, and Ella Brown must use all their wits to unravel the mystery and determine the rightful princess.