Today, I'm donating* The Silence of Murder, by Dandi Daley Mackall:
The Big Twist leapt out at me about 2/3s of the way in, so that reveal wasn't a shock for me, but I did like that it made the whole story even more of a tragedy than I'd expected it to be. (Why that pleased me, I don't know. Maybe because I don't run across Real Tragedy in murder mysteries all that often? Not counting, like, Scandinavian ones.) While the Twist wasn't a total surprise, I was surprised by the identity of the murderer, likewhoa.
*In case you missed it, I took over the running of my town library at the beginning of the month, and every day that I've worked, I've donated a book.