A prequel to the Foundation trilogy, the young Asimov's compelling, pulpish, celebrated fall-of, galactic-empire yarn. For fans of the latter, there's an annoying air of print to fit about this upstart Prelude. Young mathematician Hari Seldon visits the Imperial capital world of Trantor to present a paper on psychohistory, his newly invented mathematical tool for predicting the future--except that Seldon can see no way of making his idea practicable. Unfortunately, the Emperor thinks that Seldon has found a new way of controlling the masses--so Seldon, unable to deliver a blueprint to the Emperor, must flee and hide among the multifarious sub-societies of Trantor, pursued by Imperial agents. Thus obliged to concentrate his mind, Seldon gets glimmerings of how a useful psychohistory might be worked out. A major clue proves to be the lost and forgotten planet Earth, where--maybe--humans originated, and where--possibly--robots were invented (robots are unknown in the Empire). Promising if talky material. However, all too soon it degenerates into yet another who's-the-robot caper, like all the recent Foundations. So: an above average backdrop, and some solid if ultimately obvious plotting. Yet Seldon himself is poorly drawn and unconvincing; and the more you liked the original trilogy, the more disappointing and deflating you'll find the underlying ideas here. The one big plus: it's much better than the recent, wretched Fantastic Voyage II.