A Finer End by Deborah Crombie
Following the death of his wife and baby daughter, Jack Montford has returned to his family home in Glastonbury to try to make a new start. But then mysterious occurrencies begin and Jack seeks out the help of Winnie Catesby, an Anglican priest.
When an attempt is made on Winnie’s life, Jack is forced to call on his cousin Superintendent Duncan Kincaid to help. With Sergeant Gemma James, Kincaid rushes to Glastonbury where it soon becomes clear that the explanations behing these sinister events lie in the legendary Isle of Avalon.
(This is the seventh novel featuring Duncan Kincaid and Gemma James)