Just wrapped it up. It's a very good detective novel though I think it's political allegory sort of falls apart by the end (or at least to the wayside). Lands in a disappointing ambiguity about the role of police and borders, seeing them as both fully artificial and hostile but also necessary because the alternative is total anarchy. I maybe expected something a bit more given Mielville's clear interest in leftist politics, but it was really closer to a Dan Brown novel but

where the conspiracy is actually just a sad man with something to prove.