In the novel, the cities and regions are each ruled by their own gods. In the city of Gibil, however; the god Engibil has gotten lazy and does not monitor his city. As such the inhabitants have developed technology such as writing and smelting, and have started to lose respect for Engibil and his power. The other gods have gotten angry at Gibil for reasons they keep to themselves, and have started to refuse to trade with Gibil. It becomes the task of the main character, Sharur, a merchant, to travel the land and find out why the gods are angry and try to solve the problem.
The book received mediocre reception. One reviewer called it "an enjoyable way to pass a sunny weekend afternoon." Another states "Between the Rivers covers ground familiar to readers of Turtledove's work, however it does so in a manner which is frequently fresh and inventive."