On its surface, China Miéville’s The City & The City is a police procedural-type murder mystery set in an Eastern European city-state called Besźel. A woman is discovered dead in an alleyway, and it’s up to Inspector Tyador Borlú to find out whodunnit. Once “dead hooker” is ruled out, the case soon escalates into an international incident between Besźel and its unfriendly neighbour, the city-state of Ul Qoma, and things get more tangled from there, as is customary for the genre.

But the murder mystery’s not really the point. It’s fun and full of misdirection, but it’s the setting that’s the main draw here. Because although the city-states of Besźel and Ul Qoma act like they’re physical neighbours, with different laws, autonomous governments and strict border controls, they actually occupy the same physical space in a crazy patchwork pattern.

Here’s how it works: within the cities, some areas are completely in Besźel, others are completely in Ul Qoma, and still others are shared or “cross-hatched” between the two. A person in Besźel is allowed to walk around in the areas of total Besźel and forbidden from entering areas of total Ul Qoma. When a person in Besźel walks along a shared street with Ul Qoma (which has a different name in both cities), he must – at some pre-conscious level – judge every person and building he passes, and filter out or “unsee” any people or buildings in Ul Qoma, as signfied by certain colours, architectural styles and walking gaits, because those things are in another country. If he interacts with or even visibly acknowledges anything in that other country, he is in Breach, and this is a serious crime.

The murder mystery plot serves as a device for exploring the various ramifications of this idea, and the book goes into a lot of depth figuring out how a place like this would actually work. Drivers have to learn to drive in their own country while avoiding without acknowledging the cars in the other country. Stories are written about star-crossed lovers who live next-door to each other but in separate cities, doomed to walk right alongside each other without being able to acknowledge it.

It’s fascinating stuff, and show a very real set of human behaviours taken to their logical extreme. We all unsee other people every day, going about our business in our own personal versions of our environments, with our own areas of total (work, home, common hangouts) and alter. There’s a billboard I drive past everyday on the way to work and look at the opposite side of every day from the balcony during lunch – the side that’s facing me as I drive in is totally unknown to me. As a more extreme example, I drive down highways past squatter camps every morning on my way to my office job – the third world brushing right alongside the first world, and the first world only noticing when some poor guy decides to dash across the highway for a shortcut.

And for me as a South African, there’s apartheid, where we had separate neighbourhoods, schools, bathrooms, and lines at the post office for different races of people – but, unlike in this fiction, one of those sets were very clearly second class citizens. So as absurd as Ul Qoma and Besźel’s cross-hatched maps and meticulously kept mass delusion seem on the surface, on further inspection they reveal some truths about the stuff around us we choose to associate ourselves with and even what we choose to perceive.

If you get excited by this sort of high concept stuff and don’t need a particularly novel plot or super deep characters, The City & The City is well worth your time.