The City is an immense metropolis of crystal spires and wondrous magic. Beneath is the Dungeon, a vast underground world and a source of endless treasure, guarded by grotesque and deadly monsters. No one knows where the Dungeon came from, or why. Any who would dare face the dangers and riches of the Dungeon must first be transformed into a delver, a quasi-immortal creature whose every attribute is defined by numbers. Yet the "immortality" offered is but illusory, for without consuming the crystal found only within the Dungeon, a delver will inevitably die. One young immigrant braves the Dungeon to earn money for his impoverished family, only to find much, much more. Friends, power, and secrets of the Dungeon. Perhaps even love.
