Set in the same universe as A World out of Time but only very tenously connected to that novel, these series of two should be read as a set. The novels are set in which is not really a world. A “smoke rIng” of atmosphere and biomass orbits around a neutron star, forming a huge but habitable donut-shaped space. In other words, no gravity. Humans have colonised this “smoke ring” in various ways. Enjoyable, but more for the wickedly cool setting than for the stories.
Note: These are now also published in an omnibus edition.