A Middle School/YA steampunk adventure! 
 Set in the beginning of WWI, it pits the steam powered Clankers - machines favored by the Germans and Austro-Hungarians, versus the living weapons of the Darwinists - genetically engineered creatures of the British, French and Russians. 
 The narrative follows Alek, son of the slain Archduke Ferdinand, who is running for his life following his parents' assassination, and Deryn (called Dylan) a fifteen year old girl who disguises herself as a boy to join the British Air Service. Alek has dreams of being a normal boy, a soldier, and later, with just staying alive. Deryn wishes for the freedom that the other boys take for granted, always worried that someone will uncover her secret. 
 There are quite a few scenes of war and violence - WWI is starting and Alek and Deryn are right in it. 
 Fantastic start to the series - endearing characters, fantastic worldbuilding, nonstop action. It was a really fun read and I can't wait to get my hands on the next one.