Most good stories start with a fundamental list of ingredients: the initial situation, conflict, complication, climax, suspense, denouement, and conclusion. Great writers sometimes shake up the recipe and add some spice.
Exposition
Secrets and Lies
Well mostly secrets, with some lies thrown into the mix in order to keep those secrets. Leviathan presents us with two main characters, both of whom are keeping major secrets about their identity. Deryn Sharp is a girl who joins the British Air Service disguised as a boy, and Alek is a prince on the run from the family who's out to kill him. There's a continent between Alek and Deryn, but we get the sense that their paths are going to collide—perhaps literally—since they're both moving around in powerful war machines.
Rising Action
Can Somebody Get Us a Map?
While Alek and his companions escape to the safety of a remote castle in the Swiss Alps, Deryn becomes a midshipman on the Leviathan, where she soon learns what war is all about when the airship is so badly damaged in battle that it crash lands on a glacier high in the—you guessed it—Swiss Alps. When Deryn and Alek finally meet, the clash between Darwinists and Clankers seems like it will be too great to be overcome, until Deryn and Alek find a way to turn the crash into opportunities for both sides. This is all heading somewhere…
Climax
The Enemy of My Enemy is My Friend
Things come to a head in the great battle against two German zeppelins on the surface of the glacier. Britain is at war with Germany, and Austria-Hungary usually allies with Germany, so Alek and his gang—as Clankers—are enemies of the British airship. However, the Germans are also out to kill Alek for his grand-uncle, the emperor. Deryn, Alek, and their companions end up fighting on the same side to drive back the German zeppelins, showing us that enmity isn't as simple as it can appear.
Falling Action
Nice Engines, Bro.
Things are calm for now, but everyone knows the Germans will be back: They know there's a wounded airship on that glacier, and they know Alek's there too, so there's pretty much no way that a return trip isn't in order as far as they're concerned. Darwinists and Clankers realize they'll have to work together to get out of dodge, so Alek and his crew help the British engineers fit their totaled Clanker walker's engines to the Leviathan. Meanwhile, Alek and Deryn realize that they're friends no matter what side their countries are on. Aw.
Resolution
We Have Liftoff
With the help of the Clanker engines, the Leviathan makes it back into the sky just in time, as a German attack force appears in the mountains. Alek has joined Deryn on board the Leviathan, so now their fates are irrevocably tied together. Everything seems tied up, but there are still mysteries to solve: this is, after all, the first book in a trilogy.