Into the Dark — Matt Larkin

Zhan Lufei has returned to his family estate after ten years training at a monastery. Rather than a warm homecoming, he finds his brother distant, his sister missing, and a string of murders among the servants. Determined to find his sister, Lufei delves into the Echo -- a psychic netherworld just beyond mortal senses. In this colorless realm of ghosts and demons he finds more answers than he ever wanted.