‘The Secrets of Pain’ is part of Phil Rickman's Merrily Watkins series, books that tell the story of a single mother who retrains to become a vicar in village close to the border with Wales. As well as having to break into a tight knit rural community and dealing with the prejudices and opinions about women priests, she is also then appointed as diocese Deliverance Consultant (that's Exorcist to you and me!).
The book does work as a standalone read, but if you haven’t read any of the earlier Merrily Watkins books then you might enjoy it more if you start reading from the beginning of the series, as you will get to know the characters and the background. And surely by now Jane should know not to get into cars with strange men that she doesn't trust?