Schismatrix is a science fiction novel by Bruce Sterling, originally published in 1985. The story was Sterling's only novel-length treatment of the Shaper/Mechanist universe. Five short stories preceded the novel. Schismatrix was nominated for the Nebula Award for Best Novel in 1985.
Constantine is allowed to remain in the Republic because his knowledge is needed to keep the Republic's environment from self-destructing but Lindsay is exiled to the Mare Tranquilitatis Circumlunar People's Zaibatsu. This lunar colony, which collapsed due to an environmental crisis, has become a refuge for "sundogs", criminals, dissidents and wanderers. There he meets Kitsune, a woman modified by the Shapers to be an ideal prostitute. Apparently a servant of the Geisha Bank, a powerful money center, she in fact rules the bank through the remotely operated body of her now brain-dead predecessor. In his months on the Zaibatsu, Lindsay uses his diplomatic talents to organize a complex fraud involving a fictitious theatrical event and befriends an old Mechanist, Fyodor Ryumin. However, eventually the fraud takes on a life of its own, and the new-formed Kabuki Intrasolar becomes a legitimate artistic and business venture. Lindsay can't remain to enjoy the profits, though: Constantine has in the meantime overthrown the Corporate Republic's government. Constantine has abandoned Preservationism to become a Shaper militant, and sends an assassin to present a stark choice: become Constantine's pawn or be killed by the assassin. Lindsay manages to escape with a group of Mechanist pirates, in the process aiding Kitsune to take power of the Geisha Bank openly.
Lindsay joins a ship called the Red Consensus, which doubles as the nation-state of the Fortuna Miners' Democracy, after the failure of the previously independent asteroid-mining Mechanist cartel. The FMD, financed by more wealthy Mechanists cartels, annexes the asteroid Esairs XII, home to the Mavrides family, a small shaper clan. Lindsay meets Nora Mavrides, a fellow diplomat. Nora informs Abelard that the subjects of the diplomatic training are in disgrace due to the high incidents of treason and defection from their ranks. The two of them work to promote peaceful coexistence between the Shaper militants and the Mechanist pirates, but after several months of conflict, espionage, murders and sabotages, open fighting breaks out. Mavrides and Lindsay, now lovers, eventually murder their companions to save one another. Before the asteroid's life system dies from the battle, the alien Investors arrive.
Peace finally comes to the Schismatrix after the aliens arrive. The alien Investors are obsessed with trade and wealth, and at first encourage humanity to focus on business instead of war. Trade flourishes and the Shapers and Mechanists put their differences aside. Lindsay and Mavrides become powerful Shaper leaders, thanks to their early contact with the Investors. The Investor Peace does not last forever, though, and tensions between Shapers and Mechanists eventually start to rise when the Investors play the factions against one another. Ultimately Philip Constantine rises to power and takes control of the Ring Council, ousting Mavride's and Lindsay's pro-détente faction. Lindsay runs away from what he sees as a hopeless battle, but Nora decides to stay in the Rings, where they had built their lives and family, to fight Constantine and his militant government.
Lindsay escapes to the Mechanist cartels in the asteroid belt, where Kitsune has again secretly taken power. There Lindsay works ceaselessly for decades to bring about the detente he believes will reunite him with Mavrides. Using a recording of an Investor's ship queen involved in some taboo activities to blackmail the alien, Lindsay contributes to the creation of Cicada Kluster, neither Shaper nor Mechanist, which quickly becomes one of the richest and most powerful states in the solar system. Lindsay's partner, Wellspring, plans to use the colony to promote his post-humanist ideology, while Lindsay himself seeks to bring Nora to the new colony. However, Constantine discovers Mavride's plan to defect and forces her to kill herself. Consumed with hatred, Lindsay for the first time confronts his former friend directly, arranging a duel with him using an ancient alien artifact called the Arena. While Lindsay wins, the Arena leaves both him and Constantine catatonic.
Years after the duel, Lindsay wakes up on his old home, now renamed the Neotenic Cultural Republic. Constantine's militant Shaperism has been replaced by a Preservationist government, dedicated to remaining a cultural preserve where normal, unmodified human life is preserved. As part of the treatment that restored Lindsay's mind, his original Shaper diplomatic training has been removed. Having returned to a Preservationist world, and now restored to a fully human state, Lindsay decides to break with his past and embrace new dreams. He becomes a post-humanist and returns to Cicada Kluster to work with Wellspring. While Wellspring seeks to terraform Mars, Lindsay attempts to create an abyssal ecology on Europa. Constantine's Shaper family has been disgraced by Constantine's defeat, and Lindsay manages to convert them to his cause, even Constantine's "daughter" Vera (created from DNA taken from Vera Kelland decades before). As time goes on, eventually Cicada Kluster, in its turn, faces social collapse. With his Lifesiders faction's research still in its infancy, Lindsay and Vera Constantine secretly break the Interdict and bring back samples of Earth's abyssal life, providing the breakthroughs that make the Europa project a success.
As the Lifesiders transform themselves into fish-like forms capable of survival in Europa's oceans, Lindsay visits the now-cured Phillip Constantine. Constantine believes that Lindsay will never see Europa, that he will leave in the end rather than see his cause through to fruition, just as he always had. He also reveals that Vera's DNA comes as much from Lindsay as Vera. Phillip reconciles with Abelard, then commits suicide.
When Lindsay returns to Europa, he finds that Phillip is right-- he can't bring himself to undergo the transformation. At that moment, an alien Presence, who had followed Vera Constantine since her mission in an alien embassy, reveals itself. The being explains that it has been devoted to exploring and exulting in the variety of experiences of the universe, and invites Lindsay to join it. Lindsay accepts and is transformed into a bodiless form, to explore the infinite mysteries of the universe for eternity.