Final volume of Benford's stirring Galactic Center series (Furious Gulf, 1994, etc.). Using the energies of the huge black hole at the center of our galaxy, advanced alien ``Highers'' have created the ``esty,'' a region of space-time so crushed and compacted that it resembles matter. Here, many human and alien species have taken refuge from the marauding ``mechs,'' machine- beings hostile to organic life. Wise old Nigel Walmsley, once a physicist on Earth, now hundreds of years old, serves the Highers as a communications bridge to the Bishop clan, led by Killeen and his son Toby. But then the dreaded Grey Mech penetrates the esty, blasting Nigel and his family through a space-time wormhole to the unimaginably remote future, where the mechs are transforming themselves into electron-positron plasmas in order to survive the heat death of the universe. The Highers also prompt Nigel to rediscover a great secret embedded in the Bishops' genes: a set of infective computer codes that will destroy the mechs by subjecting them to intense pleasure. And so to a final showdown between clan Bishop and their unremitting mech foe, the soul-eating Mantis. Extravagantly, mind-bogglingly strangeyet it's the well- realized characters as much as Benford's astounding inventiveness that propel this amorphous drama to its utterly fascinating conclusion.