Set in a vast, tiered metropolis on the edge of a deadly desert, City of Bones follows Khat, a genetically engineered relic-hunter who lives in the city's lower tiers. Scavenging the ruins of a collapsed ancient civilization, Khat is hired by powerful mages to locate parts of an ancient engine—only to be caught in a conflict against a fanatical cult threatening to unleash a bone-scavenging force upon the city.