The Apocalypse Exile: The War of the Undead Novel 6 (The Undead World)

  These far-flung tribes control the interior of the country, using great armies of zombies to inflict their will upon their neighbors. For the moment they are at peace with the soldiers of Colorado and for the moment they only see in Neil and the Renegades a way to make easy money escorting them across their lands at a steep price. 
  It's a moment that can't last. 
  The specter of death lurks among the group. It haunts them and strikes again and again until its appetite is wetted to a point where it can no longer hide behind the innocent face of Jillybean. What skulks in the depths of her mind is driven by ferocious desires, chief of which is the hunger for death. It's a hunger that will never be satiated not until each and every one of them is dead. 
Betrayal, murder, war--The Apocalypse Exile.