Foundation's Edge, by Isaac Asimov (pub. 1982)
Amazon; Asimov Wiki; Goodreads; Penguin Random House; Wikipedia
Caution: I will assume that if you are reading this book, you will have already read the previous one. Therefore, anything about that book which I avoided spoiling in its review, should not constitute a spoiler for you at this point, and may be mentioned here insofar as it doesn't spoil this book...
So, the fourth book written in the Foundation series is also the first true novel, as the first three books were actually comprised of previously written short stories. "Foundation's Edge" is set in 498 F.E., over 100 years after the events of "Second Foundation." In that book, the First Foundation had created a device which could counter the mentalic fields used by members of the Second Foundation. They had also determined that the Second Foundation was located on Terminus itself, and wiped it out. However, the true location of the Second Foundation was on Trantor, and so it continued overseeing the Seldon Plan in secret, as it always had.
At the start of "Foundation's Edge," the Foundation has just gotten through its most recent Seldon Crisis, which involved choosing to keep Terminus City as the capital of the Foundation Federation, rather than moving the capital to a more central planet. This was the eighth Crisis, so the sixth and seventh must have happened sometime within the interval between books. But this one is of no particular importance to the story, other than to establish a certain degree of public support for Mayor Harla Branno. She had been in favor of keeping Terminus as the capital, and then Seldon's hologram supported her decision. However, there was a Councilman named Golan Trevize, who was convinced that the Seldon Plan was working too well; that events were proceeding too closely to the way they'd been planned five centuries ago. There wasn't enough deviation, which is mathematically... well, practically impossible. So he believed the Second Foundation must still exist, and be directing events.
Branno, taking advantage of her temporarily enhanced support, exiled Trevize. However, she too believed in the existence of the Second Foundation, and wanted to use him as a lightning rod, to draw them out, so that she could move against them. She sent along with Trevize an historian named Janov Pelorat, who wanted to look for Earth, the now-mythical planet of origin of the human race. Of course, this far in the future, it's difficult for most people to even conceive of a single planet of origin, since the galaxy has been full of inhabited planets for many thousands of years. Still, there are many worlds that have their own myths about their planet, or one nearby, being the planet of origin. Pelorat believes in one such myth, of a world called Gaia, which exists in the Sayshell sector.
Meanwhile, there is a Speaker of the Second Foundation, Stor Gendibal, who has the same feeling that Trevize has had. But while he knows the Second Foundation has been guiding the Plan, especially since the time of the Mule, he also knows there should be greater deviation. So he suspects there is another group, perhaps a whole world of "Anti-Mules," from which the Mule came. He presents his theory to the current First Speaker, Quindor Shandess, who agrees. Though there's another Speaker at the Table, Delora Delarmi, who is against Gendibal, and has the ambition of becoming First Speaker, herself. However, because of an incident in which a Hamishman (one of the people of Trantor who are simple farmers, rather than the scholars of the Second Foundation) attacked Gendibal, who was then rescued by a Hamishwoman named Sura Novi, the Council comes to accept the truth. And Gendibal, along with Novi, is sent out to search for the Anti-Mules.
Eventually, after visiting Sayshell, Trevize and Pelorat find Gaia, where they meet a woman named Bliss and a man named Dom. This is, in fact, the world from which the Mule came, but he really wasn't like the others. I'd prefer not to say anything more about the nature of the world. But soon there is a standoff between Gaia, Branno and her Foundation fleet, and Gendibal, with the backing of the Second Foundation. And Trevize is meant to make a decision about the direction the galaxy will take from this point on, though this is a position he's not happy about having been put in. Of course, I won't tell you what choice he makes.
Well. It's certainly an interesting story, all around. Once again, I'm frustrated by the virtual lack of Seldon Crises. The Plan goes on, as everyone seems to think it's necessary... or at least almost everyone. The Foundation Federation could create a Second Empire at this point, though it's only halfway through the Plan, so it would be doomed to failure in the long run. Anyway, the three-way showdown at the end represents something that's been bothering me since the third book, at least, which is that even once the Second Empire is established, things may not be ideal. I mean, that seems to be as far ahead as Seldon planned. After that, the galaxy is on its own, for better or worse. Surely it is, in a general sense, for the better. However, there is the not inconsiderable concern of who will actually be in charge. Naturally, the people of the First Foundation want to be in charge. As do the people of the Second Foundation. And Gaia has its own plans, which go beyond anything either Foundation would do. And personally, I'm not really in favor of anyone's plans, though I can see the benefit of each. So there's a part of me that hopes Seldon kept some final trick up his sleeve, which he didn't share with either Foundation. Time will tell.
There's also a plot twist which I predicted early on, and hoped I was wrong, because it was so similar to a plot twist in one of the earlier Foundation books. But... it's okay, I guess. Meanwhile, this is also the first of the Foundation novels to mention robots, which hardly anyone in the galaxy seems to have heard of, but which were integral to humanity's colonizing of the galaxy, thousands of years ago. So, this begins to tie the story into Asimov's Robot novels, and I suppose also lays the groundwork for the fifth book, "Foundation and Earth," which of course I look forward to reading and reviewing. Oh, and there's a theory about "Eternals," which has to do with parallel universes, and the fact that in this universe, only one planet developed an abundance of different life-forms, including intelligent life.
Anyway, not sure what else to say, but... it was a pretty good book, even if I would prefer to get back to stories that focus on the continuation of the Seldon Plan itself....