Another insightful, yet not very well written book from John Brunner. However, his ideas are so freshly brilliant and innovative, that the novel is hard to put down. Earth has been violently and dramatically contacted by a vastly superior alien civilization, yet alien emissaries have not bothered to communicate with mankind. Shortly before the invasion, all weapons-grade nuclear bombs and devices have been exploded which reduces most of civilization to the Stone Age, and national governments have been over-run by criminal enterprises. Then, after Earth is virtually defenseless, there appear at various locations around the globe, magical shimmering areas which could be alien cities, or possibly extraterritorial staging areas. Man's arsenal of weapons are unable to penetrate these locations, and any attempt to enter, drives the intruder insane. The remaining technically savy individuals who struggle with this unprecedented dilemma realize that mankind has entered a new and different phase. Earthlings must learn how to penetrate these alien enclaves, and learn to harness the new technology, and journey to new frontiers. Mankind must become as rats who learned how to board ancient ships, and travel to distant lands. The intellectuals who study this alien presence have discovered that it is possible to enter these areas without being driven insane, but "except you become as little children."