I was completely swept up in the plot of this book. The premise of the two cities geographically located in the same place but separated by learned and enforced psychological boundaries is absolutely fascinating and provides a new way to think about separations of class, race, ethnicity, etc. that exists outside of fiction. The idea that crossing these boundaries, without a special pass or a passport, was categorized as an illegal breach of borders and the person in breach is immediately swept way by the mysterious and unseen force called "Breach" who administer judgment in all mattes involving illegal crossing. An illegal crossing can, by the way, be accidentally seeing someone on the same street with you but who actually lives in the other country. If that other person is not "unseen" right away, the Breach step in. The characters were interesting but were admittedly they were not the main draw here. The descriptions of the cities, how they interlaced with each other, their different architecture, color, and economic differences were characters in and of themselves. The dialogue, at times, was repetitive and a bit distracting. There was too much "what's going on?", "what's up", "I don't know", "what now?", "Tell me what's going on". But it was only a mild distraction from the unique and fascinating story unfolding in the novel.