It took me over 100 pages to start caring about this book, but I did enjoy it by the end.  The opening relies a lot on setting and tone to pull the reader through, and while the setting was interesting, it wasn’t enough for me to really care about the story. 

The story opens with a corpse.  The main character, Inspector Tyador Borlú, is a homicide detective.  He investigates the dead woman’s murder. 

What makes this story special is the setting.  Borlú is in Beszel.  His city happens to occupy the same space as Ul Qoma.  Citizens in either city spend a lot of time "unseeing" the other.  If they interact with the other city, they’ve committed a breach.  There’s a special branch of enforcers (called Breach) who make people who breach vanish.  Breach is scary.  Citizens spend a lot of time making sure that they don’t breach. 

This interaction between the cities is the only speculative element in the book.  There are factions who want to join the two cities together and factions who want to limit exposure even more drastically. 

Borlú discovers that the dead woman was living in Ul Qoma, and he hopes that he can turn the case over to Breach.  Through political machinations, that ends up not happening, so he has to go to the other city to help investigators there.  The dead woman was an archeology student interested in the rumored city between Beszel and Ul Qoma. 

The investigation gets more intense and Borlú ends up committing breach.  Breach swoops in, takes him away, and recruits him.  This is when the story really got interesting for me. 

Overall, I’d give the book a 3/5.  The story is too plot driven for my taste, but it’s well written, and if you like police procedurals, even the beginning probably works.  And the ending is pretty great.