Will Gallows and the rock demon's blood

Sky cowboy, Will Gallows, is finding life hard on the ranch. Should he follow his heart and join the elf side of his family, learning their magical secrets? Or should he join the Sky Cavalry with his friend Jez? His decision is put on hold when his grandma is kidnapped - by the most terrifying creature Will has ever encountered, a rock demon with a seventy-year-old grudge to avenge.