Jack and Rosie need a vacation. They've spent years fighting the malicious fae, befriending the friendly ones, and dancing on the edge of getting eaten. Now their chaotic fae friend Calthine has made them famous for it. In search of a break, they skip town for rural Vermont, where they hope to pick some apples and wait for the spotlight Calthine put on them to dim. Instead, they get tipped from their relaxing getaway directly into Underhill, where fae run wild and humans are an invasive species. The flow of time seems to have gone crooked on them. Lassie, their brownie roommate, is lost in the woods. They try to find her and escape from Underhill only to learn that the fae are forbidden to help them by order of the Faerie Queen. Instead of Jack and Rosie finding a way out, their friends Zelda and Sarah find a way in...but in Underhill, away from all the technology that has helped them survive, it's a handful of humans against the preternatural wilderness...