For three hundred years, civilization has run on luminous ichor harvested from enormous creatures called Titans, whose fossilized bodies lie beneath the continent. It powers fortress-cities, prosthetics, rifles, airships, dungeon elevators, and motorbikes in a world of medieval fantasy, 1930s machinery, and half-understood biotechnology. Gifted swordswoman Rhea Vandel enters her first dungeon and finds Eidra, a beautiful woman sealed inside an ancient machine and wired into the dungeon by rootlike cables. Rhea thinks she is rescuing a princess, but Eidra reveals she is the dungeon itself. Every dungeon may be part of one buried biological machine, and the Titan fossils humanity has burned for centuries may be components. Something beneath the continent is waking.