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. 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.

Extras, the final book in the Uglies series, is set a couple of years after the “mind-rain,” a few earth-shattering months in which the whole world woke up. The cure has spread from city to city, and the pretty regime that kept humanity in a state of bubbleheadedness has ended. Boundless human creativity, new technologies, and old dangers have been unleashed upon the world. Culture is splintering, the cities becoming radically different from each other as each makes its own way into this strange and unpredictable future . . .
One of the features of the new world is that everyone has a "feed," which is basically their own blog/myspace/tv channel. The ratings of your feed (combined with how much the city interface overhears people talking about you) determines your social status--so everyone knows at all times how famous they are.

As Scott Westerfeld explored the themes of extreme beauty in the first three Uglies books, now he takes on the world's obsession with fame and popularity. And how anyone can be an instant celebrity.