The Secret Keeper, by Kate Morton

Kate Morton does history, love, and family with humor, insight, and suspense.  Laurel Nicholson is a very successful actress, who joins her siblings at the deathbed of their mother, Dorothy.  With the help of her brother, Gerald, she tries to get to the bottom of a violent episode she witnessed as a young teen. The violence stems from a period in Dorothy's life when she was an ambitious lady's maid and her friends Vivien and Jimmy fall in love while helping at a children's hospital in war torn London.

An Unmarked Grave, by Charles Todd

I have mixed feelings about the Bess Crawford books.  Nursing sister Bess travels all over England and France during World War I to investigate a series of murders in a way that seems utterly implausible.  The solution to the mystery comes out of nowhere in the last few pages of the book.  However, there are passages about nursing at the front, human kindness lost and found, and the suffering of the wounded that make the books compelling reading.