The Shadow Matrix

In The Shadow Matrix, Margaret has been making a desperate effort to control her new-found powers, but even the learned Tower workers cannot understand the obscure, potent, and frightening nature of her unusual matrix.
However Margaret's problems are not limited to the mystical powers of the mind, for as the rightful heir to the Alton Domain, she has become the nexus of a political battle which threatens to disrupt Comyn Concil---the governing body of Darkover. To make matters worse, she has fallen in love with Mikahil Lanart-Hastur, Regent to the royal Elhalyn Domain, a man she has been forbidden to marry, for their alliance would irrevocably alter the power balance of their planet.
But then Margaret and Mikahil find themselves drawn inexorably to the ruins of an ancient Tower---a Tower destroyed centuries ago, and they are sent back through time, to an era where every choice they make will impact on the world of their own persent. This landscape of terror eclipses all their current strife. For a long dead Keeper, one of the most powerful beings ever born on Darkover, waits for them in the Ages of Chaos. And in the quest set for them by this ancient shade they will face foes and challenges beyond their wildest imaginings in a battle which may not only change the entire face of their world, but could alter the future so that they no longer exist!