The Quantum Thief is the debut novel of science fiction author Hannu Rajaniemi. You can visit his website here.
The central character of the story is Jean le Flambeur, a legendary thief with a career that spanned centuries of time and the breadth of the solar system. Now, however, he is only another inmate in the Dilemma Prison, a virtual jail in the outer solar system where the uploaded personalities of criminals are kept for “rehabiliation” by the Sobornost, the posthuman collective of uploaded minds that is the greatest power in the solar system. His imprisonment comes to an unexpected end when he is rescued by a woman named Mieli. Mieli is no altruist, however- she and her masters have a job that requires the solar system's greatest thief. Le Flambeur agrees, feeling he owes her a debt of honor for his rescue. More importantly, the physical body he now inhabits after his release from the Dilemma Prison back into the world of flesh and blood is subject to Mieli's direct control.
But it's not just an object that Mieli needs le Flambeur to find. Much of le Flambeur's own centuries-long memory is missing. Le Flambeur's past self apparently had secrets so important that even his own memory was not secure enough, and so he hid them away in external storage external storage or locked up somewhere beyond awareness in his own mind and released only in response to particular stimuli to give his future self clues about where to find the rest of himself.
The trail left by his fragmentary memories takes them to the Oubliette, a city of (comparatively) baseline humans perpetually crawling across the surface of Mars to keep ahead of the swarms of hostile, replicating, ever-evolving machines descended from malfunctioning terraforming machinery that now dominates much of the planet. The Oubliette is a place where privacy is almost absolute, and through the electronic network that links everyone in the city each citizen can control how much other people are able to see, hear, or even remember them. Le Flambeur remembers that he once lived here, and that the place is important to him- and if there were a place where he'd secretly hide memories away, this is it.
Meanwhile, a young detective in the Oubliette named Isidore Beautrelet is helping to investigate recent murders and acts of “gogol piracy”- forcible uploading of minds. He works in cooperation with a person known only as the Gentleman, one of the tzaddikim- mysterious vigilantes who have sworn to protect the city from outside threats. His successes bringing to the attention of wealthy Oubliette citizen Christian Unruh, who has a seemingly inexplicable mystery he wants solved. This mystery will bring Isidore and le Flambeur into collision with each other, and with the truth about le Flambeur.
The Quantum Thief is an excellent book that simultaneously works very well as a character-based story, an adventure, and a novel of ideas. The central plot is interesting throughout, especially as it builds up steam approaching the climax.
Jean le Flambeur is very enjoyable as the main viewpoint character. Much of the story is told by him in the first person, and fortunately he's a fun character to follow around. The other major character's were also engaging; I was particularly fond of the Gentleman, Isidore's mysterious masked partner and mentor. (Especially once I decided that, in my head, the Gentleman would be played by The Question.) Rajaniemi does a very good job of creating characters that are clearly recognizable “types”- the roguish gentleman-thief, the mysterious woman with a painful secret, the earnest young detective and his older, more hard-nosed partner- but remain interesting, emotionally engaging individuals instead of being stock cliches.
The Oubliette is a fascinating setting with some intriguing elements. Each person is mentally linked to a citywide network that lets them exchange information and memories, while shrouded in protective encryption called gevulot that allows them to control what information about them can be accessed by others. Since everyone's mind is linked directly to the network, even the extent to which other people can see or hear you in real time, or- if a person consents through a “gevulot contract,” transmitted from mind to mind- remember you after the fact can be filtered this way. In addition to its importance to the main mystery plot, it creates an interesting situation in which people's basic psychology remains unchanged from our own but technology has radically changed fundamental aspects of social life. The hints given about the rest of the solar system are interesting as well, though are they fairly vague for the most part.
The book is very idea-heavy and set in a future where technology and society have changed radically. The technology to upload, download, or edit human minds is ubiquitous, nanotechnology and other advanced technologies have risen to almost magical levels, advanced post-humans have risen to godlike heights of power and intellect, and even the comparatively unchanged humans in places like the Oubliette, who retain a fundamentally human psychology and lives that are at least somewhat recognizable, are profoundly different from 21st-century humanity in all sorts of ways. Within this world, Rajaniemi quickly throws the reader in the deep end and mostly expects him to swim on his own. New concepts and terms come quickly and aren't always explained right away, or in depth, though as things progress it gets easier to keep up and infer things from context.
I like this sort of approach when it's done well (as it is here), since it makes it possible to put a lot of speculative technologies, setting information, and the like into the story, and can create a sort of puzzle for the reader to solve as he starts to gain enough context to understand things that were previously confusing or obscure. But it's not for everyone, and in comments I've seen from people who didn't like the book this is almost always the reason. If you do enjoy that sort of approach, though, The Quantum Thief does it very well.
I would definitely recommend The Quantum Thief for science fiction fans, especially those interested in very idea-focused SF and subjects like transhumanism. It's a somewhat iffier proposition if you're not a fan of the sort of dense take-no-prisoners worldbuilding I described above, but if that's not an absolute deal-breaker for you the story and characters are strong enough that I think the book is still worth a try. It's definitely a strong debut, and I look forward to seeing what Hannu Rajaniemi does next.