I've always thought Jane Haddam was one of the best mystery series writers, and have been impressed with how she has kept the quality high through so many installments.
In this one, though, she seeems to be trying to write a novel for which her series is not the appropriate vessel. As a result, it's one of her least successful outings.
On a bright note, her social satire on the inhabitants of Lichfield County, CT, is among her best and most pungent.
On the down side, the mystery (as another reader has pointed out) is pretty obvious, and her red herrings seem half hearted.
The real problem is that she wants to turn Gregor and Bennis into tragic star-crossed lovers or, alternatively, into poster children for the American Lung Association. The problem is that she cannot transcend how she has used those characters in the past.
As much as I have enjoyed reading about Gregor and Bennis, they remain two-and-a-quarter dimensional props to carry the mystery plot along. They can't bear the additional emotional weight she wants to pile on them here. It's like watching a semi-talented college theatrical troupe try to put on King Lear.
I suspect that Haddam probably could write a well-rounded novel about the sorts of people and issues she was dealing with here. (Every one of her novels proves that she can populate a fictional community with interesting and varigated character types.) But the Gregor Demarkian novels inhibit her amibitions. She can't be Ruth Rendell (let alone Anita Brookner ) while trying to continue to be Jill Churchill at the same time.