This book begins with a group of First Foundationers who believe the Second Foundation still exists. They also believe the Second Foundation will eventually take over the Empire once it has been built by the First Foundation. Although they basically worship Hari Seldon (which is sort of creepy) and they were defeated by the Mule (who was only stopped by the Second Foundation), they decide they need to wipe out the Second Foundation once and for all.
They send out Golan Travize to find the Second Foundation. Travize is particularly intuitive. It’s hinted that he possesses enough intuitive ability to thwart the Seldon plan.
Thus, we’ve had two individuals who can thwart the Seldon plan, which is otherwise impossible to improve upon after centuries. Make whatever excuses you want for Asimov, but that’s weird.
Anyway, through a series of events, Travize ends up at a planet called Gaia. Gaia is basically the planet that hippies hallucinated about while on LSD.
All living things on the planet are connected and work together. Throughout the Foundation and Robot novels, Asimov has been fascinated by this sort of ability – a collective consciousness, basically. Gaia is the ultimate end point of this ability. It also seems like robots are present in some form on the planet.
The climax comes when Travize (with his special decision making ability) must decide who will rule the galaxy – the First Foundation (wiping out Gaia and the Second Foundation), the Second Foundation (returning the Seldon Plan) or Gaia (returning to the Seldon Plan, but moving toward a galaxy-wide super-consciousness). He picks Gaia.
The story is well-told and it’s super impressive that Asimov is able to tie together so much of his work. On the other hand, it stretches too far in parts – some of it just doesn’t hold together.