Amherst Burial Ground - Berkley Street Series, #9

Amherst, New Hampshire, is known for its lush landscapes and pastoral beauty. It's also the home of The One, a hideous little ghost boy named Samson, who's been dead for centuries and feeds off the life force of the living. His smile is as alluring as he is deadly. Now, Shane Ryan must destroy him before Samson grants the Watchers eternal life. Shane is weary, depressed and in love with a ghost. If that's not bad enough, his depression is leading him into reckless behavior on his job.
He's no longer a ghostbuster as much as a killing machine. He's obsessed with annihilating the Watchers and their properties, one ghost and one human at a time. But his personal life is on a collision course with his professional mission and his friends are worried. When Shane finally finds Samson, the encounter is cataclysmic. With demonic glee, the lethal specter relishes the thought of killing the ghost hunter.
Fueled by hate, Shane's obsession to destroy the Watchers and Samson drives him to the edge. As events spiral into a dark place, Shane realizes their end could also be his own.