All the European powers are arming up for World War I. The Austro-Hungarians and Germans have their Clankers, steam-driven iron machines loaded with guns and ammunition. The British Darwinists employ fabricated animals as their weaponry. Their Leviathan is a whale airship, and the most masterful beast in the British fleet. Aleksandar Ferdinand is an Austro-Hungarian prince on the run. Deryn Sharp is a commoner. Their paths cross in the most unexpected way.