China Mieville has said that part of his goal in writing The City & The City was "investigating various different traditions of crime novel," especially the police procedural, and the result is part homage, part deconstruction. Yoking crime fiction to fantasy or SF can be a tricky business, not least because it's very difficult to play by the rules (such as they are).1 In The City & The City, our detective, Inspector Tyador Borlu, has a unique problem: the murder of a graduate student in archaeology has apparently been committed in the other city. Under normal circumstances, this is hardly a problem. But it's a massive problem indeed when the two cities, Beszel (Borlu's home) and Ul Qoma, overlap. Instead of being neighbors, or even divided by a physical barrier, the two cities exist simultaneously in the same area, so that in frequent cases (known as "crosshatching") the space of one city intersects and criss-crosses the other. Traffic may be on the "same" street, for example, but that street will enter and exit each city's space. To make matters far more complex, the two cities maintain their invisible boundaries by a careful psychological and physical regimen, involving everything from willed blindness to the equivalent of sumptuary laws, that constructs difference where no difference is otherwise visible. (In the most hair-raising example, drivers learn to negotiate shared streets without "looking" at the vehicles from the other city.) Those who violate the rules are "in breach," and those in breach are subject to the power of Breach, a mysterious, terrifying, and seemingly near-omniscient enclave that belongs to neither city, but patrols the boundaries of both.
In a sense, this novel constitutes a crash course in Foucault. Daily life is an ongoing process of internalized discipline: parents teach their children to act as though the child next to them (but in a different city) isn't there; adults become hyperconscious of how long they look in a particular direction, or in what direction they step; and eventually, residents of each city come to embody their citizenship in particular ways of movement. (This last becomes an important plot point.) While both cities crack down on dissidents and censor anything politically unacceptable, much of the "policing" is self-policing. In the absence of a physical boundary, the citizens think one into being. Yet this mode of perception never becomes naturalized. Borlu, our narrator, describes the world around him thusly: "The once-collapsing Ul Qoma rookeries, crenellated and lumpen-baroque (not that I saw them--I unsaw carefully, but they still registered a little, illicitly, and I remembered the styles from photographs), were renovated, the sites of galleries and .uq startups" (44). The difficulty with "unseeing," as here, is that it so often appears to happen just a little too late. Borlu never "does not see"; instead, he seeks to unsee what plainly lies before him. Breach occurs when a citizen fails to perform that crucial act of negation, when the mind denies the very evidence of its senses. In effect, the citizens are constantly at war with their own bodies (a perpetual distraction that offers some obvious political advantages for the governments). Not surprisingly, as the novel continues, it becomes obvious that playing "by the rules" involves considerable negotiation, bluffing, and, often, Breach's inattention; it is near-impossible to maintain the heightened state of absolute self-censorship that Breach requires. But this slippage is as much a feature as a bug, precisely because the impossibility of perfect unseeing generates further self-policing fear. As an avatar of Breach explains to Borlu, "No one can admit it doesn't work. So, if you don't admit it, it does" (310).
Both the physical setting and the other plot elements, including hotly politicized academic debates, conspiracy theories, religious and racial tensions, and the time frame (this isn't "our" universe, exactly, but the tech and many of the cultural references place it "now"), make it tempting to read the novel as allegory. But it's really more of an abstraction from contemporary politics, fictionalizing what they have in common, than it is a direct allegory for any one conflict. And, this being Mieville, there's no big happy ending. While Borlu does solve the murder case--complete with a classic encounter with the perpetrator at the end, right out of any police procedural--he does so only by breaching (which turns out to have some unexpected consequences, to say the least). The novel proposes absolutely no solution for the city's unique political problems: to think outside the perceptual box amounts to exile, and the various underground political organizations are either ineffective or, arguably, worse than the current regimes. That being said, Mieville certainly cocks a snook at capitalism, especially of the global variety--not surprising, if you know his politics, but it feels more tacked-on here than in his earlier novels. (Literally, given that the big revelations about who did what to whom, and why, necessarily come at the very end; while there's some set-up, Mieville understandably spends more time on the functioning of his imagined cities.)
Finally, besides the elements of police procedural, something else seems to be at work here: a parody of Dan Brown-type conspiracy novels. (In the interview linked above, Mieville mentions "conspiracy thrillers" in passing.) One of the characters, David Bowden (hmmm) is an archaeologist who destroyed his career after publishing a best-selling book, Between the City and the City, about a third city, Orciny, which supposedly exists "secreted between the two brasher city-states" (50). Orciny is purportedly occupied by "[a] community of imaginary overlords, exiles perhaps, in most stories machinating and making things so, ruling with a subtle and absolute grip. Orciny was where the Illuminati lived. That sort of thing" (50). If all-powerful invisible rulers aren't enough, Bowden glumly complains that his fans send him gibberish that he's "supposed to decode" (169). Not surprisingly, although the book is illegal in both Beszel and Ul Qoma, it has an enormous international following--despite the fact that Bowden keeps trying to recant his argument that Orciny exists--and gives rise to all sorts of further conspiracy theories, a number of which wind up infiltrating Borlu's investigation. As for the book itself, Borlu sighs, "[t]he combination of textual and historic minutiae and tendentious therefores was wearing" (142). Such heaping accumulations of apparently trivial details are all too familiar to anyone who has spent any time looking at conspiracy theories, whether in fiction or the real world. The very possibility of Orciny (where is it? what is it? who lives there? what do they do?) becomes central to solving the tale, complete with speculations about mysterious archaeological finds and long hours with cryptic scholarly annotations. Without going into further details, let's just say that there turn out to be interesting parallels between the Orciny conspiracy and the problem of seeing/unseeing, and leave it at that.
1 For a relatively accessible example of such problems, see the ST:DS9 episode "Field of Fire."