A mysterious alien race has revealed to Earthlings the existence of a great series of linking gates scattered throughout space-time. But the only gate-routes disclosed by ""the Others"" are those to and from the uninhabited Earthlike planet of Demeter. Several generations after the colonization of Demeter, a manned probe brings back a representative of the highly advanced Betan civilization. Vicious political interests on Earth hold the returned ship incommunicado; a rescue mission from Demeter manages to get away with the Betan and sets out on a Russian-roulette course from gate to gate looking for the Betan star, finally reaching the home of ""the Others"" and getting a glimpse of how this ancient race has cherished and studied humanity. Anderson's basic design is beautiful and challenging. But as in many of his narratives, the characters have a peculiarly jerry-built air (the worst being an Irish colleen of breathtaking repulsiveness). And after a few solar systems, even the scrupulous scientific descriptions--ordinarily one of Anderson's great strengths--begin to seem like so much mechanical homework. A welcome event for Anderson fans, a problematic one for others.