Leviathan Series by Scott Westerfeld, Keith Thompson

Prince Aleksander, would-be heir to the Austro-Hungarian throne, is on the run. His own people have turned on him. His title is worthless. All he has is a battletorn war machine and a loyal crew of men. Deryn Sharp is a commoner, disguised as a boy in the British Air Service. She's a brilliant airman. But her secret is in constant danger of being discovered... morePrince Aleksander, would-be heir to the Austro-Hungarian throne, is on the run. His own people have turned on him. His title is worthless. All he has is a battletorn war machine and a loyal crew of men. Deryn Sharp is a commoner, disguised as a boy in the British Air Service. She's a brilliant airman. But her secret is in constant danger of being discovered. With World War I brewing, Alek and Deryn's paths cross in the most unexpected way…taking them on a fantastical, around-the-world adventure that will change both their lives forever. less

The behemoth is the fiercest creature in the British navy. It can swallow enemy battleships with one bite. The Darwinists will need it, now that they are at war with the Clanker powers. Deryn is a girl posing as a boy in the British Air Service, and Alek is the heir to an empire posing as a commoner. Finally together aboard the airship Leviathan , they hope to bring the war to a halt... moreThe behemoth is the fiercest creature in the British navy. It can swallow enemy battleships with one bite. The Darwinists will need it, now that they are at war with the Clanker powers. Deryn is a girl posing as a boy in the British Air Service, and Alek is the heir to an empire posing as a commoner. Finally together aboard the airship Leviathan , they hope to bring the war to a halt. But when disaster strikes the Leviathan 's peacekeeping mission, they find themselves alone and hunted in enemy territory. Alek and Deryn will need great skill, new allies, and brave hearts to face what's ahead. less

Alek and Deryn are abroad the Leviathan when the ship is ordered to pick up an unusual passenger. This brilliant/maniacal inventor claims to have a weapon called Goliath that can end the war. But whose side is he really on? While on their top-secret mission, Alek finally discovers Deryn's deeply kept secret. Two, actually. Not only is Deryn a girl disguised as a guy. .. she has feelings for Alek... moreAlek and Deryn are abroad the Leviathan when the ship is ordered to pick up an unusual passenger. This brilliant/maniacal inventor claims to have a weapon called Goliath that can end the war. But whose side is he really on? While on their top-secret mission, Alek finally discovers Deryn's deeply kept secret. Two, actually. Not only is Deryn a girl disguised as a guy. .. she has feelings for Alek. The crown, true love with a commoner, and the destruction of a great city all hang on Alek's next--and final--move. The thunderous conclusion to Scott Westerfeld's Leviathan series, which was called "sure to become a classic" (SLJ). less