Marked (Apocalypse Assassins #1)

For trained assassin Dylan Romero, business is good.  As the agency's top warriors, he and partner Jake Walker are the last two people evil wants to see on the other side of a gun. When a mission takes them to the college town of Bozeman, Montana, they discover that there is more than just another mark in another town to keep them there. With a heavy concentration of vessels doing their demon masters' dirty work and flesh-craving monsters lurking around every corner, the secluded Midwest town is set to become the first battleground of the apocalypse.  The last thing Dylan needs is a distraction. With the fate of the world at stake, the life of one girl shouldn't matter - until the day she changes everything.