Shadow's End — Sheri S. Tepper

A century ago, a mysterious force wiped out human life on all surrounding worlds, leaving the planet Dinadh untouched. Now the unknown force is back--and this time humanity's only hope lies with a woman who'd give anything not to get involved. Lutha Tallstaff's mission is to locate the famed adventurer Leelson Famber, who has disappeared, taking with him what may be the only clue to the nature of the deadly threat. But Lutha cannot know that finding Famber will be the easy part of her journey. Through terrain alive with savage the holiest place on the planet. And only then will she discover the shocking truth about the coldly inhuman force that threatens the future of mankind.