She is his weakness. And she will ruin everything. Kammy Helseth's idea of adventure never amounted to more than getting a boat across to the mainland and finally escaping to London. That was until she stumbled through the mouth of the forest into a world beneath our own, the world of the Semei. Her only wish is to find her way home but when Jamie, her best friend, is taken into this new world of shapeshifters and Crystals she has no choice but to stand up to her fear and to remain beneath the surface. Hunted by Bagor, King of Alashdial, and those that are loyal to him, Kammy finds herself in the company of a group of outlaws led by Jad, a Prince with a bitter past and a similarly bitter demeanour. They overcome age-old prejudice to find a way to work together. But Bagor knows a secret about the Crystals that threatens to change everything. Kammy and Jad must find a way to thwart the king and to save Jamie, but that is just the beginning. For Kammy is in possession of a Key and the fate of countless lives, both human and Semei, may rest in her hands.