The Edge of the Cemetery - Margaret Millmore - Bog

When George Sinclair discovered he can destroy ghosts and save their victims, he became a ghost killer.
Now, George works alongside his new friends and assists the Watchers: an international group of ghost killers and supernatural experts who monitor the world for ghostly sightings and demon infestations, maintaining the balance between the living and the dead.
When San Francisco and the surrounding area are suddenly plagued by rogue ghosts and demons, the Watchers know it isn't a random occurrence. As George and the Watchers investigate, they discover that a demonic presence is behind the attacks.
With time and odds against them, they must find the source of evil and destroy it, or risk extinction of all humankind.