The Spire is a mountain of metal and stone that rises out of the middle of the desert, containing a vast city of twisting tunnels, grinding elevators, and ancient machinery, and home to over a million human and non-human residents. Sha, the last of the Medusi, is responsible for keeping watch over them as Commander of the City Watch, despite the fact she isn't shown any respect due to her race. When a string of grisly murders is committed just as a new Baroness of the Spire is about to be sworn in, Sha will have to find the serial killer and bring them to justice. But the new Baroness has a deep hatred of non-humans, and Sha will have more than one enemy at her back.