Tad Williams made his name in fantasy with the immense "Memory, Sorrow and Thorn" trilogy (1988-93). His "Otherland" quartet, opening with City of Golden Shadow (1996), is mid-21st-century SF set in an ultra-sophisticated software universe containing countless worlds. This episode features a deadly nature reserve of giant insects, a poisoned Oz, a madcap cartoon reality, London as in The War of the Worlds, 16th-century Venice, Xanadu, ancient Egypt, the … mehrOdyssey's Ithaca and the Drones Club. Otherland is the playground of the monstrously rich and unscrupulous Grail Brotherhood, who hope for on-line immortality and are abducting children's souls into their VR system. Opposing them is the enigmatic "Circle", plus a handful of ordinary folk who've penetrated Otherland and are trapped there, floating from world to world on the digital river of the title. There's a spy in this group, though; Otherland's operating system is becoming unstable; the Nemesis program that hunts down software anomalies seems murderously out of control... Williams writes fluently and evocatively, conjuring up a vivid succession of virtual realities as he manipulates numerous storylines inside and outside Otherland, climaxing with multiple cliffhangers. It's slightly frustrating, though, that halfway through the series we've learned little more--especially about the tantalizing suggestion that Otherland is a metaphysical threat to "real" reality--than emerged in book 1. Next volume: Mountain of Black Glass. --David Langford weniger