Totally cool book. Think World War I, but with Darwin's theories run amok in Britain plus Star Wars-type mechanics gone crazy in Germany. I thought the story was totally original and very fun.
Main character #1 is Alek, the would-be heir to the Austro-Hungarian throne. But after his parents are murdered, he's on the run in a giant mechanical "walker" (think Star Wars) with a few loyal followers, trying to escape the same fate.
Main character #2 is Deryn, a fifteen-year-old girl who has to disguise herself as a boy in order to fulfill her lifelong dream of becoming an airman (or, -woman, as the case may be).
Their paths cross in the Swiss Alps, where Alek had intended to hole up and wait out the war, and where Deryn's ship (a giant genetically altered whale/floating ecosystem) had crashed after a heavy German attack.
Complete cliffhanger ending, which is always a bit maddening, but it does leave a person excited for the sequel. Read and enjoy!