From Walter Jon Williams, the celebrated and influential author of Hardwired, Voice of the Whirlwind, and Angel Station comes Implied Spaces, a new novel of post-singularity action, pyrotechnics, and intrigue. Aristide, a semi-retired computer scientist turned swordsman, a scholar of the implied spaces, seeking meaning amid the accidents of architecture in a universe where reality itself has been sculpted and designed by superhuman machine intelligence. While exploring the pre-technological world Midgarth, one of four dozen pocket universes created within a series of vast, orbital matrioshka computer arrays, Aristide uncovers a fiendish plot threatening to set off a nightmare scenario, perhaps even bringing about the ultimate Existential Crisis: the end of civilization itself! Traveling the pocket universes with his wormhole-edged sword Tecmessa in hand and talking cat Bitsy, avatar of the planet-sized computer Endora, at his side, Aristide must find a way to save the multiverse from subversion, sabotage, and certain destruction.