I liked the historical accuracy and the choice of a WWI battlefield nurse as a heroine was a good one that took us right into some very interesting territory. I don't really feel that telling Maisie's life story as extended flashbacks amidst her attempts to unravel a mystery was all that effective a narrative device. I got a little fed up with Maisie looking out a window and then we spend five or six years in the past, then a couple days in the story's present, then back to the past. Not that the flashbacks were uninteresting, some of them were more vivid than the scenes taking place in the story's present.
I'm just not sure there was any great advantage to all the flashbacks vs. just a straight chronological narrative. Of course a straight chronology would have made this story into much more of an historical novel rather than a murder mystery, since the mystery only occupies the last few months of the many years covered by the tale. But as it stood I didn't have a chance to develop any sense of urgency or even much interest in the mystery, since we could so easily and frequently leave it for extended musings on Maisie's previous occupations and friendships.
There were also some exceedingly awkward sentences here and there, and some very odd transitions. So a little bit clumsy in places, but I did like the portrayal of the characters and the setting enough that I will probably take a look at the second in the series at some point.