Goliath

Aboard the Leviathan, Alek and Deryn are on a top-secret mission to end the war. But when they pick up an inventor claiming to have a powerful weapon, they must uncover whose side he's really on. As the stakes grow higher, Alek discovers Deryn's secret: she's a girl disguised as a guy who has feelings for him. In the thrilling conclusion to the Leviathan series, Alek must make a final move that could determine the fate of the crown, true love, and a great city.