I think this is chronologically the last of the Darkover novels, and also the last that was published in MZB's lifetime. Deborah J. Ross continued another half dozen or more that were "in progress at Marion Zimmer Bradley's death." Who knows what that even means? Did DJR write the rest of the books alone? Do I care? I've established that I'm horrible for even continuing to read the Darkover series given the allegations against Bradley.
But...I sometimes need to spend time in a fake world that I know well.
Traitor's Sun picks up fifteen or more years after The Shadow Matrix ends. Regis Hastur is gravely ill. His sister Javanne is still a pain and doesn't want to see her son Mikhail succeed Regis as Hastur of Hastur. 700+ e-pages of shit happens.