With Sea of Silver Light, Tad Williams completes his massive Otherland quartet, one of SF's more intriguing explorations of the eroding boundaries of the human and the non-human, the living and the dead. Otherland is a sequence that contains many secrets, and Williams plays fair by unpacking all of them in the final book. A group of adventurers, searching for a cure for comatose children, find themselves trapped in a sequence of virtual worlds, the only opponents of a conspiracy of the rich to live forever in a dream. Now, they are forced to make an uneasy alliance with their only surviving former enemy against his treacherous sidekick Johnny Wulgaru, a serial killer with a chance to play god forever. Williams manages a vast cast of emotionally involving characters with considerable panache, but the real strength of the book is its endlessly questing intelligence; it is, among other things, an enquiry into the nature of story-telling as a way that human beings give structure to their perceptions of the universe around them. It is as story that Sea of Silver Light ultimately works so well--involving us in the gruelling descent of a vast mountain, the siege of an underground fortress, gun-battles in a nightmare Wild West. Williams never neglects to tell us how things feel. He efficiently ties up every plot strand and convincingly reveals every secret in this large complex plot. --Roz Kaveney