A tetralogy of books by TadWilliams about a secretive order of superrich, superpowerful folk who have created this online construct in VirtualReality called "otherland." Something sinister about it (naturally).

# OtherlandCityOfGoldenShadow (1996)
# OtherlandRiverOfBlueFire (1998)
# OtherlandMountainOfBlackGlass (1999)
# OtherlandSeaOfSilverLight (not yet published)