The First Church. The Vatican Demonologist Files, #4

On a cliff on the western edge of Ireland, a six-century monastery has gone quiet in a way Rome cannot explain. The reports have resumed. The theology hasn't. Vatican investigator Luca Donati arrives expecting a community in crisis. What he finds is something older and stranger - a site that doesn't need saving, a system that has been running without interruption for twelve hundred years, and a structural engineer from the county council who is about to put a drill through the floor of the chapel.
Luca Donati has investigated the inexplicable before. He has never encountered something that didn't need investigating - something that was simply waiting. The First Church is Book Four of The Vatican Demonologist Files.