phenomen a book

Chief Grandvier is the leader of his people and he seeks his people''''s freedom from the humans. The current human that is in control of his tribe is the greedy Grandma Prunella. She is the current holder of the Scarf of Dominion, which gives her the power to control and summon Grandvier''''s people from their swamp that is held in a pocket dimension. He is on a quest to free his people, while he is forced to do the bidding of this greedy grandma. Can he free his people? Or are they stuck with this human untill the scarf passes to the next?