By rights, I'm just the right reader for this book: I love mysteries (especially British ones), I find WWI fascinating, I find the interwar era and the whole "upstairs-downstairs" British class stuff interesting. And yet...while mildly diverting and obviously well-researched, this first book in a series about a plucky young female investigator/psychologist really didn't work for me. It's written as if the intended readership were 10-14 year-old girls, which is fine, but as an adult, it's hard to find Nancy Drewish escapades of a flawless heroine all that fulfilling.
The framework is a little unconventional (though not the disaster some reviewers make it out to be): the first part of the book introduces us to 20something Maisie Dobbs, just opening her business in London. Her first case is a classic assignment: a man who is worried his wife is cheating on him wants Maisie to check into it. As her investigation unfolds there are allusions to Maisie's past and a mysterious mentor, but nothing is spelled out. Suddenly, the story drifts back in time to 1910 or so, and we are reintroduced to a younger Maisie as she enters service as a housemaid for an aristocratic family. We follow dutifully along as her employers discover her reading Latin in the library and extend their patronage, allowing her to be tutored by their strange friend (and apparent spy) Maurice, and eventually supporting her bid to go to Cambridge (Girton College). Despite success at school, when World War I starts, she decides to join the Red Cross, and eventually serves as a nurse in France, where she witnesses the horror of war.
The final third of the book then shifts back the the postwar era, and Maisie's patron asks her help in a family matter. This all dovetails with her earlier case, as well as the war and the scars (psychic and physical) left by the war. The mystery isn't substantial enough to satisfy most fans of the genre, and anyone with any discernment is going to find the climax painfully bad. (All I'll say is that involves singing...) As a detective, Maisie isn't particularly compelling -- her technique is a mix of keen observation and psychology. However, she's even less compelling as a character. Maisie's one of those plucky underdogs designed to provoke maximum reader projection: born into semi-poverty, raised by single father, highly intelligent, uncommonly perceptive, always composed, humble, beloved by all, and possessing big violet eyes. She's the kind of character everyone likes to imagine they would be, had they lived in that time and been born into those circumstances. The supporting cast is fairly pat: vegetable-seller father (with a heart of gold), feisty upper-class patroness (with a heart of gold), prim butler (with a heart of gold), plump cook (with a heart of gold), Cockney handyman/sidekick (with a heart of gold), etc...
The book isn't bad (except for the climax, which is terrible), it's just not very satisfying for adult readers looking for complex characters and a meaty plot. It suffers from feeling very much like a book designed to establish setting and characters for a series. I may read onward in the series (the next two are Birds of a Feather and Pardonable Lies), but may wait for the inevitable BBC TV series this will spawn.