This is a pretty good outing for Kinsey Millhone, Sue Grafton's female private eye. In this book, she's mainly in remote Nota Lake, California, working for a widow who wants to know why her cop husband was so preoccupied in the weeks before his fatal heart attack.
If I wanted to quibble, and I guess I do, I could point out that the revelation of the final clue makes no sense whatsoever: Kinsey cracks the encoding of a five-letter word the deceased has left behind. But I can't think of any possible reason for the word to have been encoded in the first place. It's not one the deceased would have forgotten.
But never mind. Kinsey's fun to follow around as she unravels things. She's insanely chatty and opinionated. And I've only recently noticed that, despite the books being written in first person, Ms. Grafton is particularly skilled in revealing things about Kinsey's character that Kinsey probably doesn't realize herself.