The Forsaken (Apocalypse Trilogy Series #2)

A DEMON hires the assassin to kill an Angel from a rival gang. It’s not the first time the hit man’s had an employer from Hell, so he checks the fine print before setting bloody quill to parchment. Just one stipulation: he’ll have to make it quick if he wants to avoid the End of the World.
The Forsaken returns us to the World of Change fifty years after the events in When Graveyards Yawn.