Theories Of Flight: Metrozone Book 2 by Simon Morden
THEOREM: Petrovitch has a lot of secrets.
PROOF: Secrets like how to make anti-gravity for one. For another, he's
keeping a sentient computer program on a secret server farm - the same
program that nearly destroyed the Metrozone a few months back.
THEOREM: The city is broken.
PROOF: The people of the OutZone want what the citizens of the Metrozone
have. And then to burn it to the ground. Now, with the heart of the city
destroyed by the New Machine Jihad, the Outies finally see their chance.
THEOREM: These events are not unconnected.
PROOF: Someone is trying to kill Petrovitch and they're willing to sink
the whole city to do it.