Our time in the Lake District wasn't long, but it was enjoyable. So I don't know why it's taken so long for me to get around to the Lake District series by Martin Edwards, even if only from pure nostalgia. Nor do I know how I at some point acquired a book from somewhere in the middle of the series. I have followed Martin Edwards' excellent mystery blog Do You Write Under Your Own Name? for some years and even read one of the books in his Harry Devlin series, which features a rather scampish Liverpudlian solicitor. So I'm really not sure what the holdup was.
In The Serpent Pool, the series regular DCI Hannah Scarlett has been demoted to the cold case squad and finds that an unexplained death has occurred at an unsettling place called the Serpent Pool, which happens to be very near where she and her boyfriend have recently bought and are remodeling a house. Meanwhile, art historian Daniel Kind, a man whom Hannah has become attracted to in earlier books of the series, has returned from abroad and is also in the area. The cold case soon becomes connected to a rather warmer one when a rare books dealer dies in a mysterious fire, and it gradually becomes clear that someone has a fetish for knocking off antiquarian booksellers.
It's not necessary to have read earlier books in the series to enjoy this one, but I think your pleasure will probably be even greater if you do.