Behemoth by Scott Westerfeld

When we last left Alek and Deryn in Leviathan, they were aboard the Leviathan (the giant living flying whale) and on the way to Istanbul on top secret business to deliver some mysterious eggs to the sultan.
As Behemoth begins, Alek and his fellow Austrians are maintaining their Clanker engines that they've attached to the Leviathan to get out of the Alps. It's a tenuous sort of peace between the British and the Austrians, if only because each knows they could not have escaped without the other, but Count Volger knows that once they arrive in Istanbul, they'll have to escape from the Leviathan, to find safety and wait out the war.
Deryn has successfully kept her secret (that she's a girl disguised as a boy to serve on Leviathan) and finds herself growing closer to Alek. And, heaven forbid, feeling like a girl towards him. She's still terrified that someone will find out (and someone DOES, but I won't say who) and she'll be kicked off the ship. She gets sent on her first command mission (which is a success and yet goes miserably).
The Austrians escape the Leviathan (something else that is a success yet goes miserably) and Alek becomes involved with anarchists, who desire to overthrow the sultan. He also meets Lilit, one of the anarchists, and a very intelligent and well trained young woman (she can pilot a walker). And an American reporter, who's too clever by half with recording bullfrog.
Deryn of course manages to be a part of this group and also comes up with a brilliant idea to help save the day. But all operations are not without loss. The Leviathan comes to the rescue once more; could this be the parting of Deryn & Alek?
Behemoth is full of action and adventure, lively moments as well as thoughtful ones, and great imagination. Perhaps one of MY favorite things about Scott Westerfeld is his portrayal of strong, independent, intelligent young women. There's a great deal of young adult literature out there starring female characters who are not so fantastic. Yes, Deryn is disguising who she is, but that doesn't change the fact that she's just as capable as the rest of the middies, and Alek. Westerfeld's character development and imagination for stories is amazing, and I eagerly look forward to the final book in the trilogy!