The year is 1914, and the world is teetering on the edge of a massive war. On one side is the British and French with their Darwinist "beasties," and on the other are the Austrians and Germans with their steampunk "clankers." This is the brilliant backdrop behind Scott Westerfeld's "Leviathan," a richly imagined fantasy story about two very different teenagers, a vast living airship, and a horde of invading German walkers. 
 One night while his parents are away, Alek is pulled out to practice his Stormwalker skills -- only to find that his tutors are actually smuggling him out of Austria to Switzerland. His father the archduke has been assassinated, and all of Austria and Germany wants Alek dead. His only hope is for a Stormwalker and a small band of loyal men to smuggle him into Switzerland. 
 In England, a young Scottish tomboy named Deryn Sharp wants to join the Air Corps... except they don't allow girls in. Disguised as a boy and renamed "Dylan," she joins the British air forces -- and after a freak accident with a floating hydrogen-breather, she finds herself on the vast floating ecosystem known as the Leviathan, the British Empire's greatest airship. And as their newest middy, she ends up being the personal cabin boy to the mildly odd Dr. Nora Barlow and her secret cargo. 
 But when the Leviathan is shot down by German planes, it crash lands on a Swiss glacier... right near where Alek and his men are hiding. And when Alek goes to take them medical supplies, he finds himself taken prisoner by Deryn -- especially since it's obvious he's hiding who he really is. Now both the Clankers and Darwinists must reluctantly join forces -- because if they don't, they'll never escape the approaching German walkers. 
 Steampunk weapons, exploding walkers, icy glaciers, political subterfuge, a snow-encrusted castle, and a giant living ship filled with talking lizards and metal-munching bats. Not many authors could pull off such a brilliantly wonky book as "Leviathan," and while the set-up of the floating whale-airship is a little far-fetched (how do those messenger animals work again?), Westerfeld manages to spin up a truly brilliant fantasy story. 
 The first half of the story is split between Deryn and Alek's respective journeys, one a grimy desperate quest across Austria, and one a lighter story about taking to the skies. But the plot really takes off when the Leviathan crashes next to Alek's castle, and from there the story becomes all about the uneasy alliance between the refugee Austrians and the desperate British. 
 And Westerfeld sprinkles the story with plenty of plot twists, mysteries and political plots within the Hapsberg family, as well as the contempt that both Clankers and Darwinists have for each other's machines (including "ungodly"). There's also a healthy dose of fiery action -- lots of explosions, machine gunning, zeppelins erupting into flames, and lots of other fun stuff. 
 But the real focus is on Alek and Deryn, and their friendship, which might end up turning into something more. They're likable characters with realistic flaws -- Alek can be a bit stuck-up, but he's generous and selfless; Deryn can be reckless in a tough situation, but she's also loyal, smart and skilled. And Westerfeld fleshes out the cast with some excellent supporting character, such as the stressed-out Klopp and Volger, or the intelligent and mysterious Dr. Barlow. 
 Scott Westerfeld's steampunk debut is a richly-imagined, well-written story that leaves the door wide open for a sequel, and leaves you hungry for whatever Alek and Deryn encounter next. A brilliant book.