Speak Justly of the Dead

‘“Never make trouble in the village” is an unspoken law, but it’s a binding law. You may know about your neighbours’ sins and shortcomings, but you must never name them aloud. It’d make trouble, and small societies want to avoid trouble.’
When Dr Raymond Ferens moves to a practice at Milham in the Moor in North Devon, he and his wife are enchanted with the beautiful hilltop village lying so close to moor and sky. At first they see only its charm, but soon they begin to uncover its secrets – envy, hatred and malice. A few months after the Ferens’ arrival, the body of Sister Monica, warden of the local children’s home, is found floating in the mill-race. Chief Inspector Macdonald faces one of his most difficult cases in a village determined not to betray its dark secrets to a stranger.
from Goodreads