Foundation's Edge

Foundation's Edge is a 1982 science fiction novel by the American writer Isaac Asimov and the fourth book in the Foundation series. It was written more than thirty years after the stories of the original trilogy, under pressure from fans and editors for another, and, according to Asimov, because of the payment the publisher offered.

It was his first novel to reach the New York Times bestseller list, after two hundred and sixty-two books and forty-four years of writing. The plot is set five hundred years after the establishment of the Foundation, with the Mayor of Terminus enjoying the political benefit of a stability that may not be entirely her own achievement.

The book's structure is a double search. One side looks for the Second Foundation; the other looks for an unknown force protecting the Seldon Plan, and both inquiries converge on the question of where human beings originated. The result is a three-way confrontation with an open ending, which is why the novel is read as the point where the series stops being a history and becomes a mystery about its own rules.