Forced from London after the death of Brunel, Thorn and her people - the Stokers - reside in the Graveyard; a wasted landscape of scrap metal and disused railway carriages. Shunned by her own people for her family's part in their exile, Thorn's skill with animals is the only thing saving her from banishment. With her friend Lurgo, she hunts the great tri-horned monsters in the surrounding swamps, desperately trying to keep control of her strange power and restore her family's soiled name. Now Brunel's old Wall is moving again, expanding over the English countryside. And with it comes a horror...