Arthur C. Clarke is one of The Big Three of classic Science Fiction (the others being Robert A. Heinlein and Isaac Asimov), and this is one of his best. Indeed, it is a classic in the field of science fiction. The recent dramatization was not awful, but nothing compared to the book. In this book his interest in the evolution of the human race (also noted in 2001: A Space Odyssey) is set in the context of a mysterious group of aliens, the Overlords, who arrive in their ships above all of the major cities of Earth. They announce that they are taking over, and they put an end to war. A Golden Age follows, but there is a final twist.