Agatha returns in another novelization. It starts off smoothly enough, a new beginning despite the the volumes that have gone before, but be forewarned it does end on a cliff-hanger.
Agatha comes for the first time to her rightful town, Mechanicsburg. Which is waiting for, longing for, a new Heterodyne. There are skeptics -- making a coffee machine helps quell that -- and a pink airship carrying a well-prepared imposter.
So it involves her learning about the Castle's problems -- it's badly broken, despite having had years of repairs from Sparks and other criminals -- Othar's being caught by a monster hunter (who just flirts with one in the Baron's service), Moloch and Agatha meeting again, the backstory of Gil and Tarvek, Agatha's walking across a narrow bridge, Gil standing off an army, and much more.