Sea of Silver Light — Tad Williams

THE END OF A UNIVERSE...

Otherland--the private, multidimensional universe created and controlled by The Grail Brotherhood, an organization made up of the world's most powerful and ruthless individuals--was crumbling. The Brotherhood's plans for immortality within the network had been shattered by the monstrous intelligence that ran the network, a presence known only as the Other, and by the even more monstrous human being who called himself John Dread. Seizing control of the network from his employer, Felix Jongleur, Dread had now made himself the god of this virtual universe and was systematically turning the network's worlds into killing grounds.

As helplessly trapped as Renie Sulaweyo, IXabbu, Sam Fredericks, Martine, Paul Jonas, and the rest of the small band who had entered Otherland in an attempt to save the many children held captive within this virtual reality, Jongleur was now forced to make common cause with his enemies. Yet even as they struggled through the maze of invented worlds, striving to reach the true heart of Otherland, time was growing short.
Caught in the surreal and deadly landscapes of the failing network, the desperate band battled against increasing odds to save the children, solve the bizarre mysteries of Otherland, and escape back to reality.

But before long there might not be a "real" world to return to for any of them. For destroying Jongleur's playground was merely a dress rehearsal for Johnny Dread. Dread's ultimate plan was to gain control of Jongleur's massive corporate holdings and spread apocalyptic destruction throughout the entire Earth....