The Quantum Thief by Hannu Rajaniemi ISBN: 0575088877
In the far post-human future, Jean le Flambeur's consciousness rots in a virtual holding cell, forced to play endless games of prisoner's dilemma as punishment for a lifelong career as a master thief . The book opens with Jean being unexpectedly broken out by Mieli, who has one last job for him but first he has to retrieve the rest of his memories. Meanwhile, both his erstwhile jailers and a detective named Isidore Beautrelet is doggedly pursuing Flambeur.
Summing up the plot of The Quantum Thief is not easy. There is a lot going on, several different factions are working to their own ends, characters are often allied but secretly sabotaging each others efforts. The setting itself is a dazzling series of fantastic locations moulded by transhuman societies. For instance, most of the action takes place on Mars, where everyone's perceptions are modified to include gevulot, a mechanism to ensure privacy by simply not allowing actions or events to be perceived unless the viewer has been expressly given the right to see and remember them via a private key system.
In fact, The Quantum Thief contains so many ideas crammed into it that there is not really room to explore the implications of any particular facet. There are no long infodumps of exposition but nearly every page contains mention of some new term or concept and the reader just has to keep up the best as they can. However, The Quantum Thief pulls off a neat trick by playing fair with the central mysteries of the plot - an alert reader can figure out revelations paragraphs before the characters can.
The Quantum Thief is not perfect. Personally I find stories of uploading mind-states, magic quantum machines and post-singularity societies pretty unconvincing, but all scifi demands some suspension of disbelief and The Quantum Thief certain rewards readers who make that effort.
Recommended if you like this sort of thing.