The Burning City - Jerry Pournelle

Set in the world of Larry Niven's popular The Magic Goes Away, The Burning City transports readers to an enchanted ancient city bearing a provocative resemblance to our own modern society. Here Yagen-Atep, the volatile and voracious god of fire, alternately protects and destroys the city's denizens. In Tep's Town, nothing can burn indoors and no fire can start — except when the Burning comes upon the city. Then the people, possessed by Yagen-Atep, set their own town ablaze in a riotous orgy of destruction that often comes without warning.
Whandall Placehold has lived with the Burning all his life. Fighting his way to adulthood in the mean-but-magical streets of the city's most blighted neighborhoods, Whandall dreams of escaping the god's wrath to find a new and better life. But his best hope for freedom may lie with Morth of Atlantis, the enigmatic sorcerer who killed his father!