Behemoth by Scott Westerfeld

Behemoth by Scott Westerfeld continues the exciting story of Deryn Sharp, the girl posing as a boy named Dylan Sharp a midshipman aboard the Leviathan, a living whale airship during World War 1 (called The Great War pre-World War II). She is friends with Prince Alex, the son of the assassinated Arch Duke Ferdinand and his wife, Sophie.

This part of their journey takes them to Constantinople/Istanbul where Doctor Nora Darwin Barlow is trying to sooth the ruffled feathers of the Sultan with a fabricated beastie still in the egg after Winston Churchill decided not to give Istanbul a ship they had already paid for, fearing that Istanbul would use it against them during the coming war. But things get bent out pretty quickly. Germans are in Istanbul and want Istanbul to join their side in the war, and as a result cause a lot of trouble for Deryn, Alex, and their shipmates. Deryn has some difficulties when one of Alex's men guesses that she's a girl and threatens to rat her out. And then Deryn and Alex are recruited by some revolutionaries to help them gain independence and hope to save the Leviathan at the same time from being shot down by a Tesla cannon. But will they be successful? This book is absolutely delightful for anyone who enjoys a great adventure story. It's especially enjoyable for fans of steampunk. I highly recommend it for adults and kids alike.