When 14 year old Briar Moss and his tart-tongued teacher Rosethorn travel to ancient Chammur. Briar stumbles across a street urchin named Ewy. The girl has remarkable magic with stonea powerful gift, since Chammur itself is made almost entirely of stone. To Briar's horror, Rosethorn informs him that since he discovered Ewy, he is responsible for finding her a teacher. Failing that, Briar must teach her himself.