Foundation and Earth (1986) is a science fiction novel by Isaac Asimov, the fifth novel of the Foundation Series and chronogically the last in the series.

Table of contents
1 Plot summary:
2 The Unwritten Sequel
3 Further notes

Plot summary:

Councilman Golan Trevize, historian Janov Pelorat and Bliss of the planet Gaia (all of whom we last met in Foundation's Edge) set out on a journey to find humanity's ancestral planet -- Earth. The purpose of the journey is to settle Trevize's doubt with his decision at the end of Foundation's Edge.

First, they go to Comporellon, which claims to be the planet on which humanity originated. Although many other planets make the claim, Comporellon has a very long history which could back up its claim. On arrival, they are imprisoned, but escape. While there, they find the coordinates of three Spacer planets. The Spacers were the first colonists from Earth. They are planets that are fairly close to Earth.

The first Spacer planet they visit is Aurora, where they are nearly killed by a pack of wild dogs, the descendants of household pets long since reverted to wolf-like savagery. They escape when Bliss manipulates the dogs' emotions to make them retreat.

Next, they go to Solaria, where they find what the Spacers have evolved into self-reproducing hermaphrodites who are individualistic to the point of isolation. They have also evoled the ability to mentally channel great amounts of energy ("transduce"). The Solarians intentionally avoid ever having to interact with each other, and only reproduce when necessary to replace someone who has died. Bliss, Pelorat, and Trevize are nearly killed by a Solarian named Bander, whom they kill in self defense. While escaping, they find Bander's child, Fallom. In the event of Bander's death, Fallom is to be killed and replaced by the other Solarians. Upon finding this out, Bliss insists that they take Fallom with them.

They next go to Melpomenia, the third and final spacer coordinate they have. They find the atmosphere has become oxygen depleted. They go in space suits into the library, and find a statue with the coordinates of all of the spacer worlds. Using that, they deduce that the location of Earth is one of two uncharted systems (Which we later learn are Alpha Centauri and Sol) While departing Melpomenia, a oxygen feeding fungus infects the spacesuits and the spaceship. They are barely able to avert disaster and disinfect themselves.

Next, they go to Alpha Centauri. They find the remanants of the inhabitants of Earth, who many millennia ago were resettled following an enviromental disaster. The natives are quite friendly, and Bliss, Trevize, Pelorat, and Fallom decide to enjoy some rest and relaxation. It turns out that the natives secretely intend to kill them. They are warned by a native woman who is sympathetic and make their escape in the middle of the night. Knowing that Alpha Centauri is the wrong system, they head towards the other uncharted system, Sol.

On the approach to Earth, they detect that it is highly radioactive, and not capable of supporting life. Instead, they are drawn to the moon. They land, and find R. Daneel Olivaw, who explains why he manipulated them all along. He says that he has been manipulating humanity for many millennia. He manipulated the galactic emperor into resetteling the population of earth to Alpha Centauri after it became too radioactive to support life; the creaction of Gaia; for encouraging Hari Seldon's study of psychohistory (A central point of the prequels to the series); and for manipulating Trevize into his decision at the end of Foundation's Edge.

Daneel explains that since the dawn of civilization, man has been divided. This was the reason for his manipulating the creation of psychohistory and Gaiai. The book ending tells us: ''"In all human history, no other intelligence has impinged on us, to our knowledge. This need only continue a few more centuries, perhaps a little more than one ten thousandth of the time civilization has already existed, and we will be safe. After all," and here Trevize felt a sudden twinge of trouble, which he forced himself to disregard, "it is not as though we had the enemy already here among us." And he did not look down to meet the brooding eyes of Fallom - hermaphroditic, transductive, different - as they rested unfathomably, on him.

The Unwritten Sequel

Foundation and Earth takes place only some 600 years into the 1000 year Seldon plan. The ending hints greatly at the next part of the story. As detailed by his wife in It's Been a Good Life, Asimov intended to write a sequel but his attempts were fruitless. He did not know what to do next. That is why he wrote the prequels (Prelude to Foundation and Forward the Foundation) instead.

The book states several times that the Seldon plan does not take into account alien influences. Combined with the ending (see above), one could surmise that for the sequel, he planned to introduce aliens (possibly the Solarians) who would upset and possibly destroy the Seldon plan.

Further notes

Although hinted at in Foundation's Edge, this book was the first book of the series that merged it with Asimov's Robot series. The radioactive earth theme was begun in Pebble in the Sky, which is set thousands of years earlier. R Daneel Olivaw's role in events would later be described in the prequels.

This book serves as a kind of epilogue to the Robot series. We get to see what has become of the Spacer worlds of Solaria and Aurora, described extensively in The Naked Sun and the Robots of Dawn respectively. We also find out what has happened to Earth, as described in Robots and Empire.