Ian Taylor & Rosi Taylor 
The Gatekeeper [EPUB ebook] 

Paul Milton, a dynamic young vicar, is successful at bringing folk back to the Church. Fresh from a South London triumph, he and his wife Sarah, an emotionally fragile English rose, head north to a new rural appointment.
However, the position is not what they expect. Soon after their arrival, Sarah becomes distant and oddly changed. Paul finds himself caught in a war between Olwen — a Celtic sorceress — and Julius Dodds, the church’s implacable troubleshooter. Under pressure from both sides, Paul suffers a crisis of faith.
As the ancient ritual of All Saints’ Eve approaches, Sarah disappears and Paul has to battle against Olwen and Dodds to save his wife from a fate too terrible to contemplate.