The Ged have come to Qom. The Ged, after warring with humans in space, can't figure out how such a volatile species could ever have achieved the ability to travel in space. The Ged are different, evolved over centuries upon centuries of communion and cooperation. They don't ... they can't ... understand the unpredictable nature of human beings.
On Qom, two factions constantly war with each other, Jela and Delysia. Each city holds unique traits to their citizens and has little tolerance for their foes. Yet when the Ged open the walled city of R'Frow to any citizen, Jelite or Delysian, promising riches to the traders and weapons to the warriors, the two factions find themselves encaged together inside R'Frow.
Inside R'Frow, they find that the Ged have changed their circadian cycles. Ayrys, a Delysian glassblower, Jehane, a Jelite warrior, Dehar, an ostracized Jelite warrior-priest, and SuSu, a Jelite prostitute, all find themselves part of the Ged plans to "observe" humans and why they've developed the capacity for interstellar flight.
Kress has built a believable world with Qom, intriguing with its alien cycles and the adaptation of the humans that live there. Plant life flourishes, and Jelite and Delysian both know the treacheries of the landscape. Archaic customs of each faction both hinder and help them through their experience with the Ged, and in the end their answer lies within their very own planet.
'An Alien Light' is a compelling story of an alien species observing humans. The aliens are really alien, and the humans are all too representative of how humans interact with each other. This is a very thoughtful "hard" Sci-Fi, with plausible scenarios through modern science stretched into the imagination of a masterful story-teller. I highly recommend this book. Enjoy!