Alas, I was right: this read qualifies for the Summer Bingo Card. As "Book Bust or Bummer."
Our intrepid heroine, nurse Bess Crawford, loses a patient, and the army, the nursing corps, and Scotland Yard all question her, trying to find out whether she was an accomplice, or was just tricked and misled. (He's wanted for murder afterwards.)
So she and her old pal, Simon (her father, a retired Colonel, is now something in intelligence, sent his former Sergeant-Major to look after her) go in search of him, to clear her name. This involves either 4 or 5 random wounded soldiers (about 2 or 3 too many), a strange misunderstanding of the Married Women's Property Acts of the 1870s and 1880s, and far too many trips to, and around, Lower Dysoe, Middle Dysoe, and Upper Dysoe. (If I never see the word "Dysoe" again it will be too soon.)
That and the motive for murder makes little sense, when it comes out.
I'll read Charles Todd again, because when they (a mother and son) are on form they write a very good read, but I guess the muse was taking an extended nap when they wrote this one.