The fact the McCall Smith publishes so many novels as year suggests that he may utilize a formula of sorts for outlining these stories.
I've never been quite so aware of that likelihood while reading The Novel Habits of Happiness. I'm not saying that a guiding formula is a negative. Only that I could see a pattern here that I've picked up in the other Isabel Dalhousie novels. I complained about one of those elements in my recent review of the short that proceeded this full length novel, but seeing it exemplified here reminds me that it's okay; that I like the Dalhousie novels for their philosophy and comfort and little joys.
Isabel is enjoying her plush Edinburgh, happy and content, when she's approached by a friend asking her to intercede with a family in crisis, with a young boy who may be recalling a past life. Then her niece, Cat, shows up with an alarming new boyfriend and her nemesis Lettuce shows up with some alarming vulnerabilities (or at least his wife does).
There's somewhat of a spoiler next: I've finally realized that McCall Smith doesn't always conclude the mysteries in these novels with a tidy bow. Those sorts of endings can be frustrating, particularly if your primary reason for reading the mystery is the resolution but in the case of this particular series, I hazard a theory that most continuing fans remain on the roster for the characters, the environment, and the philosophy. Besides, McCall Smith manages to end these never-quite-resolved mysteries so cleverly that you have to admire the deftness.
I was particularly excited for this entry into the series due to the supernatural/spiritual associations but unfortunately, what is presented as the primary plotline takes a bit of a back seat in the overall bulk of the story and also reminded me heavily of a documentary I recently watched on the same subject.
However, as I just wrote, the Dalhousie novels are less about the mystery and more about Isabel, Jamie, Charlie, and their charmed lives.