In "The Quantum Thief," posthuman gamers and privacy absolutists fight to survive on Mars

Hannu Rajaniemi's far-future thought experiment novel The Quantum Thief is about to get an American edition, and now's a good time find out why everybody is talking about this book.

Out for almost a year in the U.K., the book has been a critical hit, earning praise from popular SF writer Charles Stross and Tor editor and tastemaker Patrick Nielsen Hayden (who worked on the US edition). From the first few pages, you can see why. Rajaniemi combines swashbuckling, Golden Age-style heroes with sophisticated, philosophical worldbuilding. This book has brawn and brains - though the brains are the best part.

The Quantum Thief is set in a far-flung, posthuman future that will feel familiar to fans of Stross and Iain M. Banks. The solar system has been colonized by humans who have control of matter to the point that they can program their bodies and environments almost as easily as they can program computers. Rarefied "Zeusbrains," superpowerful AI-like entities, exercise a mysterious control over everyone's bodies and minds. And humans have divided themselves into enclaves like the zoku, devoted to a life of pure gaming, and the Oubliette, a mobile city (yes it's on legs) on Mars whose citizens are so fanatical about privacy that they edit other people's memories of them to safeguard personal information. Though we spend most of our time among these groups on Mars, we also see hints of other, stranger groups who will no doubt become important in the two forthcoming sequels to The Quantum Thief.

The novel begins with the nearly-superhuman thief Jean le Flambeur breaking out of a "Dilemma Prison," a jail where people are forced to act out the prisoner's dilemma over and over again with thousands of versions of themselves. He's rescued by Mieli, a ninja from the Oort Cloud who is on her own ambiguous mission - a mission only a master thief like Jean could help her complete. Since Mieli has basically built Jean a body and consciousness to her specifications, he has no choice but to be her servant on a strange job that takes him back to his former home in the Oubliette - where he'll figure out who, exactly, he used to be, and why his ex-girlfriend is seriously pissed at him.

Because everybody in the Oubliette has a mind that's been heavily edited for privacy reasons, character development is literally about data retrieval. And so is the novel's plot structure. The book's other main character, Isadore, is a detective trying to solve what seems at first like a routine murder case - but winds up involving Jean's pre-prison life, an impossibly rich eccentric, and a discovery that could destroy the privacy of everyone in the Oubliette. As Isadore uncovers conspiracies within conspiracies, we learn about a group of radical superhuman vigilantes who dispense justice in the Oubliette. We also visit the bizarre world of the zoku, a closed community at the edge of the Oubliette where the descendents of a former MMO guild spend all their time playing games in a simulated space that's half-virtual, half-real and all programmed. Isadore's girlfriend Pixil hails from the zoku, and their culture clash is one of the more appealing parts of the book.

There's a lot of terrific action here, plus weird plot twists that you'd expect in a scifi detective novel. How could there not be, when you've got a posthuman thief, a city on legs, and Mieli has giant wings stashed beneath the skin on her back? But the showstopper of the book is the Oubliette itself. Rajaniemi has created a world that's the logical extreme of a culture reacting against the privacy-invasions of Facebook and other social media. The Oubliette is a culture designed to prevent the online privacy breaches of today, where people can gain access to information about everything from where you eat lunch and what movies you like, to who your friends are and what you've done with your credit card lately.

People in the Oubliette have a special privacy-regulation organ in their brains, which negotiates a privacy policy with every single person they come into contact with. They can edit the memory of a conversation out of somebody's mind, or erase the memories of everyone who has seen them walk down the street. Want to have a fling that means nothing? Now you really can have sex and forget about it. Want to be sure you can enforce your NDA? Just erase your business partner's memory after you show her your new product. It's a fascinating idea, and Rajaniemi does a thorough job fleshing out exactly how you'd run a society like this, right down to the idea of quantum-encrypted memories stored in a public "exomemory" system.

The currency of the Oubliette isn't money, but the time you have left to live. Everyone in the city agrees to die every few years to keep the population down. After death, their minds are uploaded to one of the thousands of mute robot workers who run the city - after a period of labor, Oubliette citizens are born into a new body. The amount of time you live in a body is all the currency you have. So if you want to buy some fancy chocolate, you might shave a few microseconds off your life. And if you want to buy a house, you'll live less time (of course, you can earn time, too). Money is often portrayed by economists as an abstract representation of labor time, so it's a little stroke of genius that Rajaniemi has managed to figure out a world where money is literally time itself.

The only places in The Quantum Thief where the story stumbles are when Rajaniemi tries to delve into his characters' psychology. In an action novel like this one, there's no shame in having two-dimensional characters. I found myself wishing for straightforwardly depthless protagonists when Rajaniemi made a few fumbling attempts to represent complex, multi-layered relationships that span centuries. There are also a few clunky moments of purple prose, and sometimes the sheer preponderance of invented words and concepts feels more like showing off than storytelling.

I'm assuming that a lot of the ideas Rajaniemi has introduced briefly here will flower into something more detailed and meaningful in later books. That's not to say this novel doesn't stand on its own - it does - but it leaves you feeling that there's more to know.

If you're a fan of smart worldbuilding, I can't recommend this novel enough. It's a fun, far-future mystery tale and it delivers deeply satisfying plot twists. Rajaniemi has written a world you'll want to return to again.

The Quantum Thief is out now in the UK, and comes to the US from Tor this May. If you want the US edition, you can pre-order it now. (Note: The U.S. edition is the same as the U.K. edition except for spelling and a different cover.)