This mind-boggling far-future yarn should help awaken America to the formidable talents of Australia resident Egan (Distress, p. 596). By the year 2975, most humans exist only as digital electronic personalities in underground virtual-reality cyber- cities. A tiny minority, the gleisners, occupy robot bodies and insist on real-time physical interaction with the universe, and equally rare are the ``fleshers,'' who survive in enclaves on the Earth's surface. The nongendered orphan Yatima on Konishi polis temporarily occupies an abandoned gleisner body in order to bring bad news to the fleshers Orlando and Liana. The Moon-based gleisner Karpal has studied the inexplicable behavior of a pair of neutron stars that, contrary to all theory, are colliding and whose gamma- ray pulse will destroy Earth's atmosphere and make flesher life impossible. But the fleshers decide to struggle on regardless, and only Orlando is saved. By 3015, the Earth is dying, and the gleisners have launched a fleet of interstellar craft. Yatima creates the Forge group to examine the feasibility of wormhole technology. After a millennium of effort, wormhole technology proves a failure, so the polis uses its nanotechnology to create a thousand clones of itself and send them off at sublight speeds to explore the galaxy. And this is just the beginning of an amazing odyssey that will see Yatima, Orlando, and friends make alien contact, devise new cosmological theories, and pursue the mysterious Transmuters into a series of higher-dimension macrosphere universes. Vast in scope, episodic, complex, and utterly compelling: a hard science-fiction yarn that's worth every erg of the considerable effort necessary to follow.