MirrorMask (2005)

In a fantasy world of opposing kingdoms, a 15-year-old girl named Helena who works at the family circus with her father and mother, who wishes--quite ironically--that she could run away from the circus and join 'real life'. But such is not to be the case, as she finds herself on a strange journey into the Dark Lands, a fantastic landscape filled with giants, Monkeybirds and dangerous sphinxes. She must find the fabled MirrorMask in order to save the kingdom and get back home.