Tides Of Light

Now in a new, revised edition, the fourth book of the Nebula Award-winning author's Galactic Center series is a classic tale of man's future and fate, and the greatest mystery from outer space that humanity has ever encountered.
Continuing the story begun in Great Sky River, Benford creates a stunning novel of the last band of humans fleeing extinction in the Galactic Center. And with one enemy behind them, the humans are dismayed to discover on a remote planet an alien race more awesome than any they have encountered. Reprint from Spectra.