Otherland by Tad Williams
This epic science fiction saga unfolds in a near-future world where virtual reality technology has advanced to unprecedented levels, allowing users to immerse themselves in incredibly detailed and lifelike alternate universes. The narrative follows a diverse group of characters as they embark on a perilous journey through these virtual worlds to uncover the dark secrets of the Otherland network, a mysterious and vast cyberspace realm. Their quest is driven by personal motives, ranging from seeking a cure for a comatose child to unraveling the fate of missing persons, but they soon discover that their actions have far-reaching implications, challenging the very nature of reality, consciousness, and the power structures behind the technology.