The City & The City by China Mieville

I don't usually read mysteries, but this is a mystery set in a fantasy setting.
The main character is Inspector Tyador Borlu of the Beszel Extreme Crime Squad who is investigating the murder of Mahalia Geary, who apparantly was murdered in the city of Ul Qoma, which exists in the same physical location as Beszel, but, the citizens of both treat them as separate cities and they legally are required to "unsee" the other city and it's residents.  The murder victim had believed that there was a third city, Orciny, hidden in the "blind spots" between Beszel and Ul Qoma, that secretly and mysteriously controlled both cities.  Borlu investigates the murder and the belief in the city of Orciny and the relationship between Beszel and Ul Qoma as he untangles the crime that occured.  I found this book intriguing and a very good read.  This is the first book that I have read by this author and I look forward to reading others by him.