Book four in the Foundation series
by Isaac Asimov
. Copyright 1982.
Two men, one from each Foundation, are worried by the perfection that Hari Seldon's plan seems to be taking after the disruption of The Mule. Both suspect a force greater than The Mule or either Foundation is controlling humanity. Golan Trevize, of the First Foundation, sets out to find this source after he is exiled and Stor Gendibal, of the Second Foundation is sent to follow him.