Sixteen-year-old Iduna harbors a dark secret. On the surface, she is an Arendellian village girl, an aspiring inventor, and the best friend of Prince Agnarr, but she is also secretly Northuldra. Ever since the day the forest fell, Arendellians have despised and distrusted Northuldra with a vengeance. No matter that the Northuldra-along with some of Arendelle's own-have been trapped in the Enchanted Forest behind an impenetrable wall of mist since...