Foundation and Earth

The story begins immediately after the events of Foundation's Edge. Golan Trevize, a Councilman from the Foundation, an interstellar polity based on the planet Terminus, has just made a momentous choice: He selected Gaia, a planet functioning as a single superorganism with a shared consciousness across every living thing, rock, and atom, as the model for humanity's future. This decision set humanity on a path toward Galaxia, a vision in which the entire Galaxy would become one unified organism. Trevize can feel his decision is correct but cannot identify the reasoning behind it, and the uncertainty torments him. He declares he must find Earth, the legendary planet where humanity originated, believing it holds the key to understanding why he chose as he did. All records of Earth have been systematically erased across the Galaxy, suggesting something is being deliberately hidden.

Trevize departs Gaia aboard the Far Star, an advanced gravitic ship. He is joined by Janov Pelorat, a scholar from Terminus who has spent his career collecting myths and legends about Earth, and by Bliss, a young woman who is simultaneously an individual and a component of Gaia's planetary consciousness. Bliss insists on accompanying them because Gaia considers Trevize's unique decision-making ability too valuable to leave unprotected. Trevize resents her presence, viewing it as Gaia's surveillance, and the two spar repeatedly over the merits of Galaxia versus individual freedom.

Their first destination is Comporellon, an old world whose people may possess knowledge of Earth. Trevize talks his way past immigration by concealing Bliss's lack of papers, but upon landing, Comporellian security forces seize them. Minister of Transportation Mitza Lizalor explains that the Foundation has issued a Galaxy-wide request for the return of Trevize's ship. Trevize deduces that Comporellon intends to keep the ship rather than hand it over and uses this leverage to negotiate. When he mentions his search for Earth, Lizalor reacts with superstitious horror. On Comporellon, Earth is a taboo subject, referred to only as "the Oldest" and believed radioactive as punishment for its use of robots. Trevize and Lizalor become sexually intimate, which helps secure her cooperation; she agrees to let him keep the ship, partly because his search for Earth makes him an object of ill omen she wants off her world.

Lizalor directs them to Vasil Deniador, a historian belonging to the Skeptics, a rationalist group that controls Comporellon's universities and technology. Deniador dismisses the taboo surrounding Earth but admits he does not know its location. He recounts the standard history: Earth was humanity's sole home until hyperspatial travel was invented; the Spacer worlds, the earliest human colonies, were founded first; then a second wave of colonists called Settlers spread widely and built the Galactic Empire. Deniador provides Trevize with spatial coordinates from an ancient ship's log, possibly indicating three Spacer worlds.

Trevize decodes the coordinate conventions by cross-referencing with known worlds, then locates a star not recorded on the Galactic map. The Far Star proceeds to this first Spacer world, where Bliss detects animal life but no human intelligence. The planet's ecology is deteriorating without human management. Pelorat discovers an inscription identifying the world as Aurora, likely the first Spacer world ever settled. While exploring, Trevize is cornered by a pack of feral dogs, descendants of domesticated animals that have become the planet's dominant predators. Bliss rescues them by directing Trevize to use his neuronic whip, a pain-inducing weapon, on a single dog; its yelps frighten the pack into fleeing.

The second Spacer world is Solaria, where Bliss detects functioning robots and a faint trace of human thought. A Solarian named Sarton Bander greets them. The Solarians withdrew underground millennia ago and genetically engineered themselves into hermaphrodites to achieve total independence. Bander possesses transducer-lobes behind its ears that convert ambient heat into usable energy through mental power, energizing every robot on its estate. Bander claims the Spacers made Earth radioactive but professes ignorance of its current location, then announces it must kill the visitors to protect Solaria's secrecy. Bliss strikes at Bander's mind but accidentally causes a fatal energy overload in its transducer-lobes, and all power on the estate fails. In the darkened mansion, they find Fallom, Bander's 14-year-old offspring, hiding behind its frozen nursemaid robot, Jemby. When nuclear-powered Guardian Robots, which operate independently of any Solarian, arrive and declare that Fallom, whose transducer-lobes have not yet developed, will be destroyed as surplus, Bliss inactivates the robots and insists on taking the child. Trevize objects, feeling an intuitive unease about Fallom, but is overruled.

The third set of coordinates leads to an airless world Pelorat identifies as Melpomenia. In its ruins, they discover a wall inscription listing all 50 Spacer worlds and their spatial coordinates. Pelorat reasons that since these worlds were settled in the first wave of colonization, they should form a rough sphere around Earth. After correcting the ancient coordinates for stellar motion over 20,000 years, the computer calculates the sphere's center near a star called Alpha, a near-twin of Earth's sun but part of a binary system. Since Earth's sun must be single, Trevize reasons Alpha is merely a neighbor. In real space, he spots a bright unlisted star nearby and concludes it is Earth's sun.

Trevize visits Alpha first. Its habitable planet is an ocean world with a single inhabited island called New Earth, home to roughly 25,000 people. A young Alphan woman named Hiroko greets them. An elderly storyteller recounts that the Empire transplanted Earth's last population here after radioactivity made Earth uninhabitable. At a music festival, Fallom astounds the audience by using her transducer-lobes to play a flute without touching it. That night, Hiroko warns them to flee: The Alphans have infected Trevize with a virus during his sexual encounter with Hiroko, designed to kill outsiders and prevent them from revealing Alpha's existence. They escape under cover of darkness.

Approaching Earth's solar system, Bliss works to neutralize the virus in Trevize's body. They confirm the legendary details: a gas giant with an enormous ring system and a third planet with a giant satellite. But Earth is fatally radioactive, devoid of all life. Then Fallom inadvertently inspires a breakthrough by sneaking to the ship's computer and, using her transducer-lobes, focusing on the Moon visible in the viewscreen. Trevize realizes this world-sized body could harbor an underground civilization.

They descend. Bliss detects a single, powerful intelligence that is neither fully human nor fully robotic. The ship is guided into a vast underground chamber, where a figure waits. Fallom runs to him screaming "Jemby!" He identifies himself as R. Daneel Olivaw, a robot 20,000 years old, originally manufactured on Aurora. Daneel reveals he has been the hidden architect behind Gaia and the Seldon Plan, the Foundation's long-range framework for guiding Galactic history. He formulated the Zeroth Law of Robotics, holding that a robot may not harm humanity as a whole, and created Gaia as a concrete superorganism this law could protect. His robots erased all references to Earth from archives across the Galaxy to protect his existence. Daneel's robotic positronic brain, however, is failing after 600 years, and he must merge it with a biological brain to survive. He brought them here not for Trevize's brain, which is too valuable as an independent decision-maker, but for Fallom's: a Spacer child comfortable with robots, whose transducer-lobes and centuries-long Solarian lifespan make her ideal. Bliss is grief-stricken but recognizes she has no choice. Fallom, believing Daneel is Jemby, goes willingly.

Trevize finally articulates his hidden reason. Psychohistory, the mathematical science of predicting mass human behavior, rests on an unspoken assumption that humanity is the only significant intelligence in the Galaxy. But the Galaxy is not the Universe. Other galaxies may harbor alien intelligences that could invade. A Galaxy of squabbling Isolates, individuals outside any shared consciousness, would be easily conquered; only Galaxia, unified and indivisible, could resist. The novel ends ambiguously: Trevize reassures himself that no alien intelligence is already present, but he avoids meeting Fallom's unfathomable gaze as she watches him, hermaphroditic, capable of manipulating energy through her transducer-lobes, and fundamentally different from baseline humanity.