The adventures of Deryn (a girl masquerading as a boy in the British Air Service) and Alek (undercover heir to the Austro-Hungarian throne) continue in this alternative history of World War I which began with Leviathan (Simon Pulse, 2009). Intrigue and double-dealing drive the plot as the teens are swept up in a British ploy to keep the Ottomans from joining forces with the Germans. When Deryn runs into trouble on a top-secret mission from her commander she ends up in Istanbul, a hotspot of conflicting loyalties. Deryn hopes to be reunited with Alek, who escaped from the airship Leviathan . She even contemplates telling him the truth about her identity—he doesn’t know she’s a girl—as her feelings for him start to run deeper than friendship. But Alek’s alliance with resistance fighters in Istanbul raises unexpected complications, not the least of which is his friendship with a fierce and beautiful young woman named Lilit. As in Leviathan , steampunk elements and fascinating possibilities of Darwinism add to the setting of this novel, with ingenious genetically engineered creatures and mechanical wonders part of the richly imagined world. (Ages 10–14)

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.