The story occurs far, far in the future. Tens of thousands of years. There is a Human Galactic Empire that controls all the Milky Way, but it has serious inner problems and it is at the brink of collapse... or at least this is what Hari Sheldon thinks. He is the creator of a new science: psychohistory; this previses social and human behaviors to guess future political events. He thinks that after the Empire falls, the Galaxy will be at anarchy for millenia, but to prevent this, he creates two orders in the two opposite Galaxy extremes, that will create an Enciclopedia with all humankind knowings of Science, History, Politics, Economy, etc.
(This tiny introduction is only for the first book, so the other ones have a lot more interesting events, like the search for Earth, collective consciousness', telepathic abilities and more... there is also a prequel trilogy of Hari Sheldon live). The story has 9 a bit large books, but are defenitively worth it (Isaac Asimov is the writer of those books and are considered some of the best science fiction books ever). I read the whole series and I loved it, unfortunately I don't have apple subscription to watch the Apple life-action series...