12-year-old Prue McKeel lives in the quiet town of Portland with her parents and little brother Mac, who just turned one year old. Parents often send their children for walks together, and during one of these walks, a flock of ravens kidnaps Mack and takes him to the Impenetrable Thicket, located behind a ravine and enjoying an evil reputation. Prue has no choice but to pluck up courage and, together with her school friend Curtis, go in search of her brother in a mysterious forest, behind the trees of which lies a completely different world, full of magic and danger.