'Alek and Deryn are aboard the Leviathan when the ship is ordered to pick up an unusual passenger. This brilliant, maniacal inventor claims to have a weapon called Goliath. It can end the war. But whose side is the inventor really on?
While on their top-secret mission, Alek finally discovers Deryn's deeply kept secret. Not only is Deryn a girl disguised as a boy ... she also 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.' (Publisher's blurb)