What if you weren't . . . you?
(What if you were a writer _telling the story_ of someone in that situation? How would you organize it?)
If you're the protagonist in this fascinating SF novel, you're probably in for some interesting experiences. But will you get to keep them?
(If you're James P. Hogan, you tell the story in chunks, cycling through the various nonoverlapping personalities and telling the parts of the tale for which each is "present," as it were.)
Who do you turn out to be? Are you one person or several? Which hero saves the day, and which hero _gets_ saved? Are they the same person? Are you sure?
Hogan is in fine narrative form here. I've seen his writing described as "textbook-dry," but that's not likely to dissuade those of us who regard, say, Kernighan and Ritchie's _The C Programming Language_ as the pinnacle of expository prose style. Hogan writes like a _good_ engineer; his prose does the job he wants it to do, and the meat is in the story. (You don't need mannered digressions about the splendid colors of the autumn leaves in a book whose theme is that the universe isn't what you think it is.)
In fact this is a fun book, full of Hogan's trademark mind-blowing coolness. The underlying technology is rendered plausible and the story is interesting from beginning to end. Even if you know what must be going on -- and you will, by midway through the second chapter, even if you hadn't figured it out from the title -- you'll still be kept guessing until the very end about (a) how and why it happened, and (b) how it will ultimately turn out.
Hogan is one of my two favorite living SF writers (the other is Spider Robinson, who doesn't write "hard" SF). If you like SF, you'll like him.