Fia is a human changeling raised in the royal court of Caelum who is tasked with rescuing the kingdom's true heir from the magical Fair Isle. To break the curse that turned the princess into a swan, Fia must infiltrate the dangerous High Court of the Fae and navigate its deadly politics. There, she forms an uneasy alliance with a dark fae prince while uncovering secrets about her own heritage and the true nature of the magic binding the two realms.