When fourteen-year-old AnnaGrey meets a horned horse-like creature called an aeobanach in the forbidden Wildwood, she crosses the threshold from our world to a magical one in the hope of finding answers about her night-vision ability. She's only too eager to leave everything behind-her mom's secrecy about the past, her dad's far-fetched tales, and especially the mean boy at school, Cross Silverstone. She and the aeobanach embark on a journey to create a potion that will change the aeobanach into its human form. But their quest is complicated by rebels seeking to overthrow a king who's more interested in finding his long-lost son than ruling a kingdom.

After being captured and accused of being a rebel against the throne, AnnaGrey learns she might know where the king's son, Silverstone, is. The king makes her a deal: bring his son back to the magical realm, and he'll not only release her aeobanach, but he'll help AnnaGrey discover the truth about herself. AnnaGrey must convince the boy who bullies her-who may be a kindred spirit in disguise-to come with her to the magical world so she can free her friend, get information about her night-vision ability, and go home-where the true answers about her abilities lie.