I reject the idea that this is an "urban fantasy". Admittedly, it takes place in a city, Tenochtitlan, capitol of the Mexica Empire. There are definately magical and supernatural things going on, not to mention a little human sacrifice. Finally, the most common plot of UF is present, the investigation of supernatural crimes. Okay, there might be a few reasons this gets filed under urban fantasy, but there are no vampires, no werewolves or even werejaguars, and no fae. I would file this under Aztec Mystery.
In Acatl's Tenochtitlan the continued survival of his people depends upon the goodwill of the gods. As High Priest of Mictlantecuhtli, Lord Death of the Underworld (known as Mictlan) Acatl is asked to investigate the disappearance of a beautiful priestess. The only clues are the bloodsplattered room and that someone summoned a jaguar spirit. The only known witness, and obvious suspect, is his brother Neutomoc, a wealthy Jaguar Knight.