Swanwick's third fantasy (The Dragons of Babel, 2008, etc.) set in an industrialized Faerie bristling with weird entities.
Curious readers will learn that this is just one of many worlds (Aerth, or Earth, is another) that are "different energy states of the same place...the surfaces of an n-dimensional tesseract." Now you know. Caitlin Sans Merci serves in Her Absent Majesty's Dragon Corps as the pilot of a malevolent iron dragon, 7708. The Corps' purpose is to steal children's souls from Aerth so they can be embedded in soulless high elf bodies; Cat herself is one such. As her story opens, she returns from a raid discovering that somehow she's acquired a secret stowaway in her cranium, the mysterious Helen V. from Aerth. Soon, Cat's half brother, Fingolfinrhod, a full-blooded elf, will inherit House Sans Merci from their dying father. Fingolfinrhod, appalled at the prospect, instead vanishes (after warning Cat of a conspiracy against her) into what Cat will later learn is the city Ys, drowned long ago beneath the waves. Cat, framed by her superiors and betrayed by 7708, flees, determined to clear her name and reclaim her position. The scintillating narrative, sprinkled with black humor, bulges with symbols and allusions to topics in science, alchemy, magic, folklore, mythology, fantasy/science fiction, and literature. Remarkably, all the major and most of the minor characters are female, not to mention an alluringly innocent protagonist. A few signs warn that Swanwick's extraordinary inventiveness may be running down, with recycled characters and scenarios and too-frequent passages where descriptions lapse into itemized recitations, like laundry lists. Still, these are minor blemishes in what is primarily another bravura performance, with a surprise ending that, after a moment's reflection, isn't so surprising after all.
Discworld meets Faust. They do not like each other. Philip Pullman picks up the pieces.