Isaac Asimov was a prolific writer of books, which included both science fiction and non-fiction science related books. Over the years, he has become extremely famous for the numerous science fiction novels he wrote, and the way he wrote about societies of the future. His societies of the future have a certain tinge of familiarity with the society that we can see now, but he also showcases societies which seem extremely warped in terms of how they operate (especially when you see the societies that he has described in the Spacer worlds).
Asimov was born in Russia and moved at a very early age to the US and settled down in the Brooklyn area of New York. Although he was associated with different universities including Columbia and Boston University and even spent some time in the army (having been drafted), his heart was always in writing. He became a contributor to the famous science fiction magazines of the time, and also moved into writing science rather than science fiction. Isaac Asimov is most famous for the series of short stories and novels he wrote on Robots (and played his part in removing the Frankenstein complex about Robots through his Three Laws of Robotics - although the development of military robots seems totally contrary to these law of robots and seems more fueled towards the Terminator kind of world).
He also wrote a series of books that are collectively known as the Foundation Series (the first three of which came in the early 1950's and the remainder were written after a period of 30 years). They explore a period in which the massive Galactic Empire that has kept peace in the Galaxy is decaying and will eventually die, causing a prolonged period of anarchy and a scientist attempts to reduce this time period to a much smaller interval.
The novel is the 4th novel in the series, starting with the The Caves of Steel, The Naked Sun, and The Robots of Dawn. The main difference between these 3 novels and this one is the non-presence of the team of Elijab Baley and his humanoid robotic partner, R. Daneel Olivaw. The time period is set around 2 centuries after the previous novel, which means that Elijab Baley is no longer on the scene, having died as per human timelines. However, the lady he met in 2 of the previous novels, Gladia Delmarre, is still alive since she is a spacer and spacers have developed a much longer lifeline than that of humans.
But there has been a great transition in the overall balance of power in the galaxy. In the time of Elijah, the spacers were very powerful while earth was a much weaker source of power. However, the movement started by Elijah and a few others and supported by the faction of spacers led by Dr. Han Fastolfe, who wanted the settlement of the galaxy to be done by humans rather than using humanoid robots, grew wings and the humans started spreading outwards, outpacing the spacer worlds and using the huge population of earth to settle new worlds.
Even though Dr. Fastolfe had died, his enemies were still in place and could not digest what was happening, and were not able to withstand the increasing number of worlds being populated by human settlers. They want to destroy Earth in a way that is not traced back to the spacers and they believe that this will ensure that earth is not able to achieve its aims. In all this, is present a descendant of Elijah Baley, called Daneel Giskard Baley, who is part of these groups of settlers. He wants the help of Gladia for help in figuring out why her now abandoned planet of Solaria is destroying spaceships that land there, and also wants to recover the robots that are now there, apparently without any owners. Gladia decides to help, and gets Giskard and Daneel (with their super strength) as companions.
The former opponent of Dr. Fastolfe, Kelden Amadiro has got a new supporter and helper, Levular Mandamus. Till now, Giskard has been able to use his telepathic powers to stop all efforts by Amadiro to stop earth, and now he and Daneel have to proceed on their most difficult fight as yet, the effort to stop Amadiro and Mandamus from destroying earth through an increase in radioactivity (the net result of which was displayed in a mostly radioactive earth, in Pebble in the Sky). However, while trying to stay in line with the Three Laws of Robotics while trying to stop these 2 is a big challenge, and Asimov tries to get more inventive, trying to create a Zeroth law of Robotics, which places humanity above individual humans, but this effort places a huge impact on the minds of the robots and causes a breakup of the minds of Giskard. And the earth does become radioactive, but not in a few years, but over the next 150 years.
Asimov tried to use this novel to link his robotic series with his Foundation series, using Daneel in the last of the Foundation series and also introducing the worlds of the spacers as dead worlds.