City of bones
(Book)

"The city of Charisat, a tiered monolith of the Ancients' design, sits on the edge of the vast desert known as the Waste. Khat, a member of a humanoid race created by the Ancients to survive in the Waste, and Sagai, his human partner, are relic dealers working in the bottom tiers of society, trying to stay one step ahead of the Trade Inspectors. When Khat is hired by the all-powerful Warders to find relics believed to be part of one of the Ancients' arcane engines, he, and his party, begin unravelling the mysteries of an age-old technology. This they expected. They soon find themselves as the last line of defense between the suffering masses of Charisat and a fanatical cult, bent on unleashing an evil upon the city with an undying thirst for bone. That, they did not expect."--,Provided by publisher.