Castle of Shadows — Ellen Renner

Ever since the Queen mysteriously disappeared and the King went mad five years ago, eleven-year-old Princess Charlie has lived a wild and mostly unsupervised life in the country of Quale -- until now. With the discovery of an unfinished letter in the Queen's handwriting, Charlie embarks on a quest to find her mother and save the kingdom from a revolution. With Tobias, the gardener's boy, by her side, every step closer to the Queen pulls Charlie deeper into an entangling web of lies and secrets -- as twisted as the dark castle -- where nothing is as it seems.