For the first time, I'm not connecting Grafton's title with the subject of the mystery she's written. Yes, the title is explained (and particularly, it's explained how this is not the correct word to use for a riptide effect), but even in a metaphorical sense it doesn't work. For me, I think that's the case because "undertow" could describe the characters in every single one of her mysteries. They are all sucked in and floundering and panicky.
I really do think Grafton is ramping things up for her last 8 or so novels (she has 6 to go), though. The writing is both taut and descriptive and entertaining, and she got to have a lot of fun this time describing how hippies can not be a barrel of laughs, plus how hard it is to be a writer. For the latter, she creates a character learning to write as a teenager and becoming a hugely successful mystery writer 25 years later. Cute, but the only problem with this is that this kid has a deep dark secret, which I can just imagine the press trying to get to the bottom of. "Ms. Grafton, does this mean YOU have a deep dark secret you'd like to share with us?"
There is one place the story falls down-- at the end, and this is where Grafton can sometimes fail us. She spends quite a bit of time with a hapless yet likeable young man, getting us to feel sorry for him, and then never revisits the ramifications of his life and his family at the end. I needed that, didn't you?