Rivers of Sand (Eno the Thracian Book 4)

The fourth title in the best-selling fantasy series that began with Hero for Hire.
All monsters dispatched from carnivorous geese to minotaurs. Special rates for multiples. Eno the Thracian at the sign of the Ram’s Head, one flight up.
When Eno is transported by the whim of a god to the desert lands of Mesopotamia, he promptly stops an attempted murder. Dropped into the middle of a demon's vengeance on a Babylonian goddess, Eno must help the endangered citizens of the most infamous city on earth. Soon he has too many clients, none of whom seem willing to pay him even as much as a shiny stone. But when an all-powerful queen and the Goddess of Desire both demand his services, the fee is surely the least of Eno's problems.
With a foolish prince and an incompetent sorcerer by his side, Eno must defeat the demon, stand off an Assyrian army, and escape from his most dangerous predicament yet – being King of Babylon. Monsters he can handle but politics? That's a beast of a different breed.