Harbinger - The Eldritch Series

On All Hallows' Eve, the barrier between the living and the dead is thinnest. Nicholas Harwood has inherited an unusual job-keeping the dead quiet. For several nights before All Hallows' Eve, he pours a potion derived from a family recipe on the graves of the late residents of Dante's Hollow to keep the dead from walking. So far, he's been successful. But something-in addition to snow-is in the wind, and he can't stop it alone.
Nicholas and his unlikely group of companions-a druid sorcerer, a witch, and a ghost or two-are locked in a power struggle with rogue supernatural powers intent on unleashing great evil.