The aliens appeared one day, built a base on the moon, and put an ad on the internet:
"We are an alien race you may call the Atoners. Ten thousand years ago we wronged humanity profoundly. We cannot undo what has been done, but we wish humanity to understand it. Therefore we request twenty-one volunteers to visit seven planets to Witness for us. We will convey each volunteer there and back in complete safety. Volunteers must speak English. Send requests for electronic applications to witness@Atoners.com."
At first, everyone thought it was a joke. But it wasn't.
This is the story of three of those volunteers, and what they found on Kular A and Kular B.
"Probability Space offers the pleasures, delivered, with all Kress's unfailing intelligence and skill, of lovers united (though not without the possibility of future heartbreak), villains defeated (though other villains remain available and willing), actions completed (as much as they can be in a world of flux), and puzzles solved (except for the stubborn ones buried in the human, or alien, heart)."
Locus
"She is so deft in supplying background information that I had no trouble understanding the characters and the desperate situation they find themselves in....I look forward to reading more about this metaphorically rich variant in the social contract."
New York Times on Probability Space
"Kress's always excellent characters wrestle with a splendid array of puzzles and problems, human, alien, and scientific; another resounding success for this talented, sure-footed writer."
Kirkus Reviews (starred review) on Probability Sun
