Helwyn

The Helwyn are demon hunters born of Hell, outcasts in the realm of demons. Rejecting evil, they have walked through Hellfire, a fearsome trial of purification to purge Hell from their souls. Cleansed of the curse of evil, they hunt Hell’s dark forces on earth, using age-old ballads as a road map to find these creatures and send them back to the Underworld.
Helwyn is the first book in the series and is based on the ballad Lady Isabel and the Elf Knight, about the world’s first serial killer. Ballads are, after all, man’s first urban legends...