If I had known before I bought the first Merrily Watkins novel (The Wine of Angels) that Merrily is an exorcist, I probably would have saved my money. But I didn't know, and now I'm hooked.
The characters are fabulous - Merrily, the sometimes hapless vicar; Jane, the pagan daughter; Gomer, the archetypal local; Lol, the fragile folk-rock mystery. Any and all of these will fix your attention and concern, to say nothing of a wide array of secondary characters and ghosts. OK, the ghosts sound hard to take, but Rickman carefully constructs Merrily's vocation, making the line between spiritual work and work with spirits very faint indeed. The vicar's faith is remarkably practical and so are most of the problems she faces.
The plots grow out of the settings on the Welsh border, exquisitely detailed in all the books. In Smile of a Ghost, the town of Ludlow becomes another character, in some ways the principal victim. Of all the books, this one has the most subtly integrated element of the supernatural: you can take it or leave it.
If the exorcist plot makes you nervous, start with this book and see if your concerned affection for Merrily, Lol, Jane and others doesn't over-come your hesitation.