"Have you ever thought you saw something out of the corner of your eye, but when you looked properly, you didn't see anything? Or thought you heard something, but when you really listened, there was nothing there? Well, you are seeing and hearing things that are there. Things that are Unseen." All around us there exists a world just on the edges of what we call Real--a realm of underground forests beneath the sewers, goblin markets held in empty parking lots, and witches living just a few houses down the street. For siblings Thomas and Jayne, a walk through the woods behind their new house suddenly plunges them into this new world and sends them running for their lives. Lost, afraid, and pursued by a group of shape-shifting children, Thomas and Jayne have no choice but to accept the help of the only one who comes to their aid: the sinister Locust Man. Their new guardian--the clueless, but well-meaning Desmond--follows his cousins into the same strange magical realm, and will stop at nothing until he rescues them from the Locust Man and brings them home again.