Imre Bergamasc has arrived at Earth, although what he encounters is not what he expected. He is faced with a rebellion that doesn't want to hand over the planet to him and led by Jasper, a man who claims to be God. Told from Jasper's point of view, one that does not follow time in the usual way, we get to piece together the events of Imre arriving on Earth and the resulting battle between the two sides leading to a conclusion that is fitting.
Set in the same universe as his Astropolis books, Cenotaxis is a short story that takes place after Saturn Returns but before Earth Ascendant. As it's told from Jasper's viewpoint it's an interesting story, we see Imre and his colleagues differently, although each are still unmistakable. Jasper is also a good character, one that can live future parts of his life before ones in the past. This is surprisingly easy to read and the way he experiences time fits the story very well.
I'd recommend Cenotaxis without hesitation, although how it fits into the overall story arc is not yet clear to me - it comes across as an extended prologue rather than a stand alone, but I couldn't tell you whether this will be related to Earth Ascendant - that's one I'll be reading fairly soon to find out.