It is the year 12020 of the Galactic Era.  Cleon I is the emperor of a Galaxis that is slowly and unnoticed slipping away towards decline.  There are no real new inventions, technology is not optimally maintained anymore, and of some devices nobody is really sure how they function.  A young scholar, Hari Seldon, presents his theory that the behaviour of large groups of people could be mathematically calculated. The emperor is interested, not so much for the predictions, but for the possibility that they could be used for propaganda.  After all, if people believe that a certain future is going to happen, they will start acting like it.  But Seldon believes that though he can prove his theory might work, making it workable would prove to be impossible, and he refuses to cooperate.

On his way home a journalist saves him from a couple of muggers, and convinces him that it would be better to go into hiding.  And what better place than the University, where there is hardly no imperial interference, where there is enough information available to help Seldon build his psychohistory, and where the journalist, Chetter Hummin, can find him a historian to assist and protect him.  Seldon isn't convinced he can develop the psychohistory at all, but he'll give it a try.  After a few weeks he needs a break, and goes along with a few meteologists to the roofs of the domes that cover almost the entire surface of the planet Trantor.  Up there he feels observed and chased, and hides, but the low temperatures and the snow are almost fatal for him.  Was there really something, or was it pure paranoia?

Hummin takes no chance and sends him, together with the pretty historian Dors Venabili, to another safe haven on the planet.  At least, it would be safe, if Seldon's curiosity doesn't make them break some of the holiest rules on that section of the planet...

Chronologically this is the first of the Foundation novels and stories, but reading at least Foundation first is not a bad idea.  There's little explanation about anything, the story starts on page one.  And in contrast to the two previous novels the story is a successful blend of Asimov's typical logically reasoning conversations, and an adventure novel that takes Hari Seldon and Dors Venabili all over the planet.  Furthermore it builds on on the previous novels where Asimov's Robot novels are brought together with the Foundation and Galactic Empire novels.

In the best Asimov tradition the characters, credible as they are, are not too deeply explored.  And in this same tradition the story itself is supposed to carry the novel, and in contrast to the previous two of the series this time Asimov certainly succeeds in that.  Taking the protagonists to a few rather opposite environments makes it easy to use strange or exotic habits and cultures, but they only serve as "decoration", the story could be, except for the technology used of course, just as well have happened here on Earth, about in our era, without loosing anything of its strength.

And the end is even a surprise, it's only in the last few pages you notice that the entire novel has been building up to this.  It just shows the skill of master-narrator Asimov: we know psychohistory will come, we know Seldon will survive and use his science.  What surprises could a prequel offer?  Remarkably many, from the hesitations of a groping scholar via his adventures in his first months on Trantor to the double surprise near the end of the novel.  It sure makes it easier to forget the weaknesses of the previous ones.