Dust and Decay

I have recently read the book Dust and Decay by Jonathan Maberry. This book is about a 15 year old Benny Imura and his older brother Tom Imura in a post apocalyptic world. Tom Imura is a famous bounty hunter in this world and he took Benny and his friends under his wings. Bad things happen out in the bounty hunter world, a bunch of the bounty hunters kidnap children from local towns. Tom Imura and his group are trying to put a stop to it.

The theme of this book is most likely along the lines of something along the lines of 'always be wary of everything around you'. I feel like this is the theme because most of the time the bounty hunters are the good guys... but they can also be the bad ones.