Behemoth by Scott Westerfeld
Behemoth is the second novel in the trilogy by Scott Westerfeld. The trilogy is a steampunk/biopunk retelling of WWI, where instead of trenches and outdated tactics, there's floating air whales and land battleships. The book continues the story of Prince Aleksander, son of Archduke Franz Ferdinand, who was assassinated in Serbia, and Deryn, a girl disguised as a guy so she could join the British Air Service. In the trilogy, the Central Powers are replaced by the Clankers, who are countries that use machinery, and the Darwinists, who use genetically enhanced creatures grown in vats that hatch from eggs in warfare. Behemoth is a great novel, with an easy to follow plot, interesting characters, and plenty of action and details, accompanied with illustrations to help you picture the monstrous creatures utilized by the Darwinists and titanic machines used by the Clankers. However, if you haven't read the first book in the series, Leviathan, you'd probably be lost on what's happening in the plot. If you plan on reading this series, I would recommend starting with the first book, which you'd think would be a given, but I've read the second or third book in series before reading the first several times(is it just me?).