tl;dr: Crux (affiliate links: Amazon, B&N, Book Depository) is some really, really excellent science fiction. You should be aware that it is the second in a series.
The beginning: Isn’t this a veritable cornucopia of characters for me to remember all at once. Damn. The gist of all this appears to be that there is a mental enhancement program called Nexus with some serious implications for human evolution. Its ?creators? ?adapters? are on the run from the law (in fact, on the run from the law + a whole bunch of bounty hunters). They are also trying frantically to stop various brands of bad guy from using Nexus as a weapon.
The end (spoilers in this section only! Skip this paragraph if you don’t want to know!): I hope So-Yong Shu gets explained more fully as the book goes on, because this ending implies that she is important. Anyway, at the end, someone called Shiva dies; Rangan goes free; and So-Yong Shu takes over her daughter’s body. I guess that answers my question about whether she’s a good guy or a bad guy.
The whole: I will tell you why I am hereby recommending Ramez Naam without reservation. Two thirds of the way through this book, I was crazy enjoying it and not wanting to put it down; nearly all of my confusion about the characters had been cleared up; and the plot was crackling along like wildfire. I paused to think about how I was ever going to write a synopsis of this book’s premise, given its weirdness and the multiplicity of characters and the international scope of the thing; and I glanced at the back cover to see how the publishers wrote the synopsis. They wrote this:
Six months have passed since the release of Nexus 5. The world is a different, more dangerous place. In the USA, the freedom fighters of the Post-Human Liberation Front use Nexus to turn men and women into human time bombs aimed at the President and his allies. The first blows in the war between human and posthuman have been struck.
You would not believe how slowly the cogs began to turn from here. First cog: That synopsis is awful! Doesn’t even explain what Nexus is! Second cog: This reads actually like the synopsis of a sequel to a book about Nexus. Third cog: Wasn’t the Ramez Naam title on my TBR spreadsheet Nexus? And not Crux?
Then I stared at the front cover for a while and had some doomed arguments with it like,
Me: You are called Nexus.
Front cover: CRUX, by RAMEZ NAAM
Me: But you are called Nexus!
Front cover: CRUX, by RAMEZ NAAM
Me: But! But!
Back cover: The dazzling sequel to Nexus
Y’all, I don’t know. I have no excuses.
The takeaway here should not be that I am a moron (though I plainly am), but rather that Ramez Naam must be pretty good for me to get so caught up in a book that — I realize belatedly — presupposes an awful lot of knowledge of these characters and this world. The weak link was So-Yong Shu, who may have been interesting in the first book, but who in this one is just in a holding pattern for almost the whole book. The rest of the characters have a lot to do, and Naam is brilliant at giving a sense of stakes to many different characters and plotlines.
Anyway. I refer you back to the tl;dr, above. Crux is wonderful science fiction, and I recommend it very much. But, like, probably you should read Nexus first. Probably, Crux will make a lot more sense to you in that case.