Arthur and Maudie Brightstorm receive devastating news: their famous explorer father has died in a failed attempt to reach South Polaris. To make matters worse, the Lontown Geographical Society finds Ernest Brightstorm guilty of sabotaging the expedition of his competitor, Eudora Vane. But a mysterious clue leads the twins to question the story they've been told-and to uncover the truth, they must undertake the journey of a lifetime.

Joining the ragtag crew of a homemade sky-ship captained by the intrepid Harriet Culpepper, Arthur and Maudie race to South Polaris to salvage their family's reputation and find out what really happened on their father's doomed expedition. Brightstorm is a propulsive and compelling fantasy adventure set among the vibrant landscapes and dynamic characters of Vashti Hardy's vividly imagined world.