The latest from Barnes (Mother of Storms, 1994, etc.) opens on Mars early in the 22nd century, where Joshua Ali Quare wakes from a long illness with only scattered memories; among his few possessions is an advanced computer containing hundreds of documents, many contradictory, detailing his past lives. Born in 1969, the son of an American communist, Joshua was quickly recruited by the KGB, then infected with a virus that, every 15 years, renders him helpless. When he recovers, ready to assume a new identity, he's ten years younger -- but most of his memories are gone. After the collapse of communism, Joshua continued to work for the Organization, whose object had become power and profit rather than ideological conquest; he worked by intimidation and assassination to promote or suppress scientific discoveries. In a later incarnation, he fought in the War of the Memes, where various artificial intelligences and their ""memes,"" copies of computer programs capable of taking over human brains, vied for dominance; eventually, the Earth was converted into the anthill-like Resuna. Joshua barely escaped to Mars. Now, he discovers that his old war buddy Sadi has become a woman -- and immortal; not only that, but she's taken over the Organization -- and perfected a method of time travel that gives her almost unlimited power to remake the world to her own desires. Meanwhile, a rescue fleet from 300 years in the future heads back for a showdown with the dangerously expansionist Resuna. Grim, sinewy, consistently surprising, and -- despite Barnes's habitual, and always irksome, present-tense narration -- unforgettable.