One Grave at a Time (Night Huntress, #6)

Having narrowly averted an (under)world war, Cat Crawfield wants nothing more than a little downtime with her vampire husband, Bones. Unfortunately, her gift from New Orleans' voodoo queen just keeps on giving-leading to a personal favor that sends them into battle once again, this time against a villainous spirit. Centuries ago, Heinrich Krammer was a witch hunter. Now, every All Hallows Eve, he takes physical form to torture innocent women before burning them alive. This year, however, a determined Cat and Bones must risk all to send him back to the other side of eternity--forever. But one wrong step and they'll be digging their own graves.