This is the prequel to the Foundation series with spoilers so should be read after "Foundation and earth". In "Prelude to Foundation", the happenings in the centuries before Asimov's other Foundation novels are now revealed. It is the year 12,020 GE, and Cleon the last Galactic Emperor of the Autun Dynasty, sits uneasily on the throne. Young Outworld mathematician Hari Seldon arrives on the scene with a theory of prediction that Cleon believes his future security may rest on. Hari becomes the most wanted man in the Empire as he tries to keep his theory from falling into the wrong hands and also to forge the key to the future: a power to be known as the Foundation.