This final book in the Merchant Princes/Empire Games series is a conclusion to very different set of books Stross started twenty years ago.
Invisible Sun attempts to detangle the cascade of events that Miriam triggered when she first time-walked into a new timeline by accident and began a business venture that changed worlds. In many ways it succeeds as a conclusion—many characters find satisfactory new paths forward and plot lines are tied up or blasted to a shattering end.
When viewed through other lenses, however, it falls short. It's often confusing to juggle the multiple timelines with crossings of characters, overlapping dates, and almost similar locations. While time pressure drives the plot, it often feels rushed in an inexplicable manner.
It is very helpful for the reader to be familiar with, at a minimum, the first two books of the Empire Games trilogy (Empire Games and Dark State). It is a much richer story for those who take the time to meet Miriam in The Bloodline Feud.
Are there challenges with this conclusion? Yes. Overall, this book, which Stross himself has said was written under a curse, is a satisfying read that provides closure to the story line.
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