Four books where psychiatrists take center stage

At The Barnes & Noble Book Blog Ellen Wehle tagged "four mind-bending books, in which therapists and the life of the mind take center stage," including:Waiting for Wednesday, by Nicci French

One problem I have with non-police mysteries is credibility: why would your average priest/granny/piano tuner be able to solve a tricky murder case? The best mysteries make me believe it, as in this series