A novelization of the first major StoryArc of the award-winning webcomic series ''Webcomic/GirlGenius'', released in Jan 2011. It follows the webcomic ''very'' closely, often having a distinct 1:1 mapping between panel and paragraph, but it does have a few interesting departures.

''Agatha H. and the Airship City'' is a gaslamp fantasy adventure starring Agatha Clay. As the novel starts, she is an assistant at Transylvania Polygnostic University who gets caught up in the arrival of Baron Klaus Wolfenbach, the iron-fisted ruler of most of Europa. She also seems to have ties to the heroic Heterodyne Boys, who vanished years ago.

* AdaptationalAngstUpgrade: A minor one. In the original comic, Gil complains on seeing Theo that he never replied to his letters, but quickly moved on. Here, the students of Castle Wulfenbach make mention of having sent letters to Gil he never replied to, and they're greatly hurt by the apparent snub. Why exactly the Baron (or possibly Von Pinn) felt the need to drive a wrench between his son and his friends is not explained.
* AdaptationExpansion: Not much, but there's a number of small added details and background info, particularly with Krosp and his creator Dr. Vapnoople. See also the EarlyBirdCameo.
* TheArtifact: Sleipnir, or at least her name; in the original comic she was called that by the Foglios because she was Agatha's roommate who Sleeps Near her. In the novel, Agatha gets stuck with Zulenna.
* CoversAlwaysLie: The US version of the cover attempts to depict the scene where Agatha and Gil battle the slaver-wasps on board the airship. Except Agatha is wearing the wrong outfit, Gil has been replaced with Krosp and a Wulfenbach clank, and the wasps with.. giant toothy mechanical snakes. Or tentacle-claws. Or something.
* EarlyBirdCameo: The prologue is set 16 years before the main story starts and focuses on Bill and Barry Heterodyne. Both characters have only been seen in flashbacks and stories in the web comic.
** The Corbettite Railways also get a mention, with the Baron placating a complaining town council by offering them a shiny new railway station.
* {{Foreshadowing}}: Othar's comment upon being told by Agatha that she is ''not'' The Baron's Beautiful But Misguided Daughter: "Are you sure? I'm usually very good at spotting the offspring of evil geniuses."
* FriendlessBackground: Agatha, in part due to her general social awkwardness, constant moves while she was growing up, and also because Professor Beetle tended to have ''words'' with anyone who tried to approach her.
* TheFriendNobodyLikes: Zulenna, on account of being arrogant and haughty, and the only one on-board Castle Wulfenbach who gives a damn about the pecking order. She and Agatha don't get along, not helping when one of her comments when they first meet touches a nerve with Agatha.
* FunnyBackgroundEvent: Wooster and Zoing's fight.
* FunetikAksent: The Jäger/Mechanicsburg accent.
* ItTastesLikeFeet: Sleipnir's favorite cheese, which no one else can stand.
* KidsAreCruel: Agatha was repeatedly bullied as a child, on account of children noticing she didn't fit in. It was one particularly horrible case that drove the normally inattentive Barry to move to Beetleburg. Subverted with the mention that one of Agatha's most treasured possessions in Beetleburg is a small cow sculpture an unnamed boy gave her at some point.
* MilitaryMoonshiner: Moloch
* {{Novelization}}: It's the novelization of the webcomic that started out as a regular print comic. This may surprise some readers who were led to expect more of a ''spinoff'' and instead got a very direct prose adaptation.
* ObfuscatingStupidity: The Jägers, constantly, even moreso than in the original comic.
* OutsideContextProblem: The Other, when it first arrived. This is how it got its name, because it killed all of the other people that it could have possibly been.
* ScrewThisImOuttaHere: Hinted at, while Agatha's walking home from the university, several shopkeepers and residents of Beetleburg are already packing up shop in a big hurry.
* SecretLegacy: At the end of the book Agatha learns that she is the daughter of Bill and Lucrezia Heterodyne and heir to one of the most powerful of Spark dynasties.
* SensoryOverload: Agatha suffers a mild version of this during the first week after she loses her locket. This implies that her locket didnít just suppress her Spark but her other senses as well.
* ShellShockedVeteran: From the description of him in the prologue this is what Bill Heterodyne has become after the destruction of his home, death of his son, disappearance of his wife, and three years of fighting the Other.
* UncertainDoom: The last time Bill and Barry were seen together by anyone (who is talking, anyway) was over a decade before the story starts, helping the survivors after another attack by The Other. The last Adam and Lilith heard from Barry, it was from a vague and garbled note shoved under their door while they were out.
* WorldHalfFull: It's made evident in the {{Fictional Document}}s at the beginning of each chapter.
* YouGetMeCoffee: One of the added bits. Right after the Baron walks off alone in Beetleburg (to show he can), the Jägermonster in charge tells two of his Jägers "Go get me coffee, from that shop on the other side of town, and don't let him see you!" This is his roundabout way of giving the Baron an armed guard - without ''appearing'' to give him an armed guard. Who says the Jägers aren't schmott?