Just outside the Spin, an artificial collection of suns and planets that's existed for hundreds of thousands of years, a man on a dying world watches, as he comes to the end of his own life, knowing that the artificial solar system he's studied from afar is close to the end of its as well. He never expected the chance to actually visit the Spin, but a visitor suggests that may be possible, and that might be something worth seeing before his death. Meanwhile, another man with a past spends most of his time visiting the virtual realities, simulations of real people and real societies, many of which don't know they're simulations, that exist within the Spin.
The third book of this loosely linked trilogy (all involving the Spin, but largely unconnected in terms of characters or plot), and it's probably the most successful of the three. It doesn't quite live up to the promise offered by the early parts of the first, but is at least more cohesive, and although it suffers from the same problems as the other books in the series, they're not as bad.
The biggest problem is that it's a book where the main characters are essentially bounced around to various set pieces, with some vague goal but not much agency in it, and seems more like they're just an excuse to show off various ideas the author had. In each previous book, I've mentioned it reminds me of the story style of Iain M. Banks, but not as skillful, and so it is here. But, the author's getting better at it. At least in this one the two plots meet in a way that, although not entirely unexpected, at least somewhat satisfied, and although the revelations and solutions didn't entirely feel earned it's more or less an enjoyable jaunt throughout. I still think the series could have been much more, and that disappointment might be the actual greatest sin, but I'm, if not satisfied, at least don't feel as though I completely wasted my time. Although granted, the fact that I bought all three books as an ebook bundle for very cheap might play into it.