The collection begins as Agatha finds a new ally in Krosp the Cat (a genetic experiment with a smattering of Napoleon's brain cells) and becomes better acquainted with Gilgamesh, the Baron's son - who gently breaks the news that Agatha has the spark for Mad Science. Othar Tryggvassen escapes the Baron's lab as the Monster Engine is activated by a revenant, and pandemonium ensues on the city-sized airship as Agatha and Gil battle the awakened behemoth. Adam and Lilith arrive in time to make crucial explanations about Agatha's identity and attempt her rescue, but are devastated by the Baron's forces, and Agatha and Krosp must make their dramatic escape alone.