The Uplift War-a deep-future conflict that spans both galaxies and centuries-continues in this rich middle volume (after Brightness Reef) of Brin's second Uplift trilogy. On the planet Jijo, the painfully developed cooperation among six sapient races (humans included) is rapidly crumbling under the impact of contact from space. The visitors include the dolphin crew of the ship Streaker and the Rothen, the race who may have ""uplifted"" to intelligence most of the races of Jijo, except the humans, who because of their unique status are in greater peril than ever. The ensuing tale is well paced, immensely complex, highly literate-and a daunting read, particularly for those new to the series. On full display here is Brin's extraordinary capacity to handle a wide-ranging narrative and to create convincingly complex alien races that not only differ from humanity but also variegate internally. By novel's end, Jijo is irremediably altered, its status as a world of refugees from the political chicanery of the Five Galaxies likely gone forever. Once again, Brin has created a successful mix of social speculation and hard SF that puts him in the honorable company of such authors as Charles Sheffield and Gregory Benford. Undeniably, this is demanding SF; but just as undeniably, it is superior SF as well. (Dec.) FYI: Two Uplift novels have won major SF awards: Startide Rising, the 1983 Nebula Award for Best Novel, and The Uplift War, the 1988 Hugo for Best Novel.