The Shattered Gears — Jeff Somers

Avery Cates is a bad man. Wandering the ruins of The System, he thinks he's done fighting, done killing -- but the world hasn't quite ended yet. When Cates is trapped in an old System prison, he encounters evidence that he's still a person of interest, and this leads him on a journey of revenge and discovery that pits him against the psionic Angels, the remnants of the System Police, and those who pass for power brokers in this new, shattered world.