A Summer in the Twenties - Peter Dickinson
I had originally thought this belonged in the category "Literature and Fiction" but it turns out it does conform to the genre "Mystery" in many ways. This is not really a bad thing, but it does lead to the biggest let-down about the book.

The protagonist of this story, Tom Hankey, is unusually intelligent and perceptive; over the course of the book, his understanding is called on at both personal and societal levels. Mystery stories have a problem-solving focus; unlike in technothrillers or science fiction, they are social problems. There's a stereotype, left over from the early years of the genre, that detection hinges on untangling train schedules and alibis; but in more recent books, and certainly in any that I'd actually find interesting, it's really about reading people -- deciphering their motivations, their relationships, patterns of influence.

In A Summer in the Twenties, it was really a pleasure watching this process of understanding; plus, Tom's insistence on thoroughly considering the moral implications of his (and other people's) actions was refreshing. But, when you introduce a subject as large as the labor policy and revolutionary ideas that are discussed here, it's a shame to give them too superficial treatment. One thing about mysteries is that problems have to have solutions in order for the conventions of the genre to be fully met (many more recent examples are darker and more ambiguous, though). I've gotten beyond feeling satisfied by a denouement in which a villain is stymied in a single confrontation. Even when the problems involved are confined to a single family, I don't feel like they can be satisfactorily wrapped up very speedily. The biggest weakness of this otherwise good book is that it fits convention all too well in this respect.