The Foundation, established after the Old Empire gives way to barbarism, fights against a mutant strain called the Mule and tries to get rid of the Second Foundation after learning it will inherit a future Empire.

Led by its founding father, the psychohistorian Hari Seldon, and utilizing science and technology, the Foundation survived the greed and barbarism of its neighboring warrior-planets. Now cleverness and courage may not be enough. For the Empire—the mightiest force in the Galaxy—is even more dangerous in its death throes. Even worse, a mysterious entity called the Mule has appeared with powers beyond anything humanly conceivable. Who—or what—is the Mule? And how is humanity to defend itself against this invulnerable avatar of annihilation?

The Foundation lies in ruins—destroyed by a mutant mind bent on humanity’s annihilation. But it’s rumored that there’s a Second Foundation hidden somewhere at the end of the Galaxy, established as insurance to preserve the knowledge of mankind. Now a desperate race has begun between the survivors of the First Foundation and an alien entity to find this last flicker of humanity’s shining past—and future hope.

Yet the key to it all might be a fourteen-year-old girl burdened with a terrible secret. Is she the Foundation’s savior—or its deadliest enemy?

Golan Trevize, former Councilman of the First Foundation, has chosen the future, and it is Gaia. A superorganism, Gaia is a holistic planet with a common consciousness so intensely united that every dewdrop, every pebble, every being, can speak for all—and feel for all. It is a realm in which privacy is not only undesirable, it is incomprehensible. But is it the right choice for the destiny of mankind?

While Trevize feels it is, that is not enough. He must know. Trevize believes the answer lies at the site of humanity’s roots: fabled Earth . . . if it still exists. For no one is sure where the planet of Gaia’s first settlers is to be found in the immense wilderness of the Galaxy. Nor can anyone explain why no record of Earth has been preserved, no mention of it made anywhere in Gaia’s vast world-memory. It is an enigma Trevize is determined to resolve, and a quest he is determined to undertake, at any cost.