Romulus Buckle and the Luminiferous Aether (The Chronicles of the Pneumatic Zeppelin Book 3)

"Preston's Steampunk series is not just entertaining and fun but full of great characters who deepen and change over the course of the books. Expect amazing Steampunk scenes, yes, but also people you care about and a lovely mix of the comic and serious. Just pure storytelling at its best."--Jeff VanderMeer, author of the Southern Reach novels

Earth is an ice locked wasteland, devastated by an alien invasion hundreds of years before. Left with only steam power, the human survivors formed into steampunk clans. And now these clans are at war.
Reeling from a Founders clan invasion, Captain Romulus Buckle of the Pneumatic Zeppelin faces a desperate decision. Does he return home to bolster the Grand Alliance or attempt to rescue his sister, Elizabeth, who is prophesied to be the key to winning the war? With only an ancient automaton and the words of a madman to guide him, Buckle leads an expedition to the mysterious underwater city of Atlantis, where mythical monsters and human treachery make every move perilous.