Memory — Linda Nagata

Acclaimed hard-SF author Linda Nagata introduces a new world, where the sky is bisected by an arch of light, and the mysterious "silver" rises from the ground each night to completely transform the landscape--and erase from existence anything it touches.

Young Jubilee is devastated when her brother Jolly is taken by the silver. But when a forbidding stranger with the power to control the silver comes seeking Jolly--and claiming that Jolly knows him--Jubilee flees. For she has learned an impossible secret: Jolly may still be alive!

Jubilee's flight will lead her to discoveries she could never have imagined, from the secret history of her civilization, to the awesome forgotten memories within her. And with these she will forever alter her world's future... unless the dark stranger, relentless in his pursuit, achieves his goal of destroying it.