Nancy Kress is one of my favorite living short story writers. In fact, I think we can scratch the "living" and just say that she's one of my favorite short story writers. Her Beggars in Spain is The SF Novel That Changed My Life--I read it at just the right time, and I think it's safe to say that the course of the rest of my life has been different because of it. But for me her novels depend pretty heavily on speculative premise. With some writers I am willing to read pretty much anything they write, on the theory that other aspects of the book will more than make up for a shaky speculative premise. That's true for me with Kress's short stories. Her novels, not so much so.
Steal Across the Sky...is one of those books it's hard to talk about without spoilers, because it's a two-climax structure: there's one big reveal in the middle and then a snowball of events follows that. I felt that the big reveal in the middle was telegraphed from pretty early. In any case, there are aliens who have shown up and told humanity that these aliens once did something really bad to humanity and wanted to atone.
They are not notably successful with the atonement. On so many levels. I hate to complain about aliens being kind of incomprehensible, because in some ways that's a good thing, if they're sufficiently alien. On the other hand, there's a middle ground where they look less alien than like humans with a lot of guilt and a half-assed approach to mitigating it. Which is I guess okay too.
Mostly I never got caught very well by the central premise. One character was described as "incomprehensibly" being not very interested in the "big bad thing" the aliens did to the humans 10K years ago. I have to say that in his position, I would not only be not very interested once I knew what it was, I would be resoundingly pissed that I had been taken to an interesting extrasolar planet with interesting social and technological stuffs, only to be whisked away immediately once I had seen what someone else decided was the single unifying important thing about my visit there. It's like if someone said, "We will give you a free trip to London!" and I said, "Yay!" and they said, "Now you have seen the hotel we selected for you! You see what your room would have looked like if you'd gotten to stay here? Good. You're going home now!" We saw approximately nothing of this not-very-interested character, nor of anyone else who had any other reaction to the alien cultures in question than to fixate on the thing that the alien culture told them to.
So--aliens doing kind of weird alien things: good. Humans getting one-track about them: not so great. Not a bad book, but not, I think, one that will stand above Kress's other work.