This was apparently originally intended as the first volume of a series (probably a tetrology). It was copyrighted in 2000; but Norton died in 2005, and her co-author (Sasha Miller) may or may not have had sufficient material to go on with the series. Because of this, the book is surprisingly inconclusive, even for a Norton work. To use her own favored metaphor of the ruthless weavers of Fate, there are loose threads all through the story, and none of them are really dealt with.
Not much of a loss, I'd say. Many of the characters are thoroughly unpleasant people. Norton seemed to have had a somewhat jaundiced view of character, and didn't show much sign of mellowing with age.
The setting is a world undergoing a natural disaster. An extraplanetary impactor has significantly increased vulcanization, and there's a fairly great probability that no humans will ultimately survive.
This is a fact that is largely ignored by the characters, although they do notice movements of displaced people--sometimes. Far from putting aside their petty quarrels, they pursue them with even more passion, like people looting what they can get while a fire is still raging. Nobody seems to think of uniting to do anything that might save them. One character comments that, if they don't stop squabbling, the earth will probably swallow them up--but then dismisses the thought as peripheral, because it's not like we actually CAN change, is it?
It might be interesting to see what a more sanguine (and less sanguinary) person would have made of the same basic premises. Norton was almost unexceptionally contemptuous of negotiation, which she seems to have regarded as always a matter of selfish plotting, and more harmful to the participants than outright, relentless slaughter. Others might differ in such conclusions--though not Sasha Miller, apparently, based on this and other books he collaborated on.