This was the fifth of Asimov's robot novels.

Asimov had three SF series that he was famous for: the Foundation series, the robots, and the "empire" series.

Towards the end of his life the Good Doctor wrote several books attempting to tie all three of these series together. This was one. "Foundation and Earth" was another.

It used to be said that there was the "Big Three" in science fiction: Asimov, Robert Heinlein (The Puppet Masters, Starship Troopers) and Arthur C Clarke (2001: A Space Odyssey and its - film and prose - sequels). And then there was everyone else.

Asimov and Heinlein may be gone, but they leave behind a massive legacy.