Seek the scattered Storm-Opals of Sea, Sky and Land, before an enemy finds them and uses them to wield dark power ... The trail of the Storm-Opals takes Mouse further than she has ever been before. With her little brother Sparrow and friend Crow alongside her, she stumbles into the world of Sky, where fortresses are hidden amongst the clouds, secret libraries (skybraries) nestle atop gigantic icebergs and the sky swirls with warring tribes and their ferocious flying beasts. Can they solve Da's message before it's too late for their ship, their tribe and the whole of Trianukka? Sky-soaring, beast-chattering, dream-dancing, draggle-riding, terrodyl-flying, world-saving adventure.