Phil Foglio & Kaya Foglio - Girl Genius Novels (#1-3)

Agatha H and the Airship City (Girl Genius novels #1)
Adventure! Romance! Mad Science!

The Industrial Revolution has escalated into all-out warfare. It has been eighteen years since the Heterodyne Boys, benevolent adventurers and inventors, disappeared under mysterious circumstances. Today, Europe is ruled by the Sparks, dynasties of mad scientists ruling over—and terrorizing—the hapless population with their bizarre inventions and unchecked power, while the downtrodden dream of the Hetrodynes’ return.

At Transylvania Polygnostic University, a pretty, young student named Agatha Clay seems to have nothing but bad luck. Incapable of building anything that actually works, but dedicated to her studies, Agatha seems destined for a lackluster career as a minor lab assistant. But when the University is overthrown by the ruthless tyrant Baron Klaus Wulfenbach, Agatha finds herself a prisoner aboard his massive airship Castle Wulfenbach—and it begins to look like she might carry a spark of Mad Science after all.

Agatha H and the Clockwork Princess (Girl Genius novels #2)
Intrigue! Subterfuge! Circus Folk!
In a time when the Industrial Revolution has escalated into all-out warfare, mad science rules the world... with mixed success.

With the help of Krosp, Emperor of All Cats, Agatha has escaped from the massive airship known as Castle Wulfenbach. After crashing their escape dirigible, Agatha and Krosp fall in with Master Payne's Circus of Adventure, a traveling troupe of performers dedicated to staging Heterodyne shows - dramatizations of the exploits of Bill and Barry Heterodyne and their allies - who are unaware of Agatha's connection to the Heterodyne line.

Pursued by the ruthless Baron Klaus Wulfenbach, his handsome son Gil, and their minions (not to mention Othar Tryggvassen, Gentleman Adventurer), Agatha hides in plain sight among the circus folk, servicing their clanks and proving herself adept in performing the role of Lucrezia Mongfish, nemesis to - and later wife of - Barry Heterodyne. She also begins training under Zeetha, swordmistress and princess of the lost city of Skifander. Together, Agatha, Krosp, and the performers travel across the treacherous wasteland of war-torn Europa, towards Mechanicsburg, and the ancestral home of the Heterodynes - Castle Heterodyne.

But with many perils standing in her way - including Wulfenbach's crack troops, mysterious Geisterdamen, savage Jagermonsters, and the fabled Storm King - it's going to take more than a spark of Mad Science for Agatha to get through.

Agatha H. and the Voice of the Castle (Girl Genius novels #3)
In the third installment of the Girl Genius novels, Agatha H. and the Voice of the Castle begins as Agatha Heterodyne returns to her ancestral home, the warped little town of Mechanicsburg. There she must claim her inheritance by convincing the artificial intelligence that animates her family’s castle that she is, in fact, the new Heterodyne. But this apparently simple task is made complicated in several ways: An imposter claiming to be the legitimate heir appears. The Empire is convinced that Agatha is the person responsible for the Long War (and to be fair, they are not entirely incorrect). And, worst of all, the Castle itself is insane.