Cat Among the Pigeons by Agatha Christie
I know to trust Agatha Christie, but her international thriller-type books are not my favorite. So, when Cat Among the Pigeons started out with a revolution in Ramat, I was a bit worried. Prince Ali Yusef is preparing to leave the country, but before he does, he entrusts his good friend with a fortune in jewels, asking that they be gotten to England and to the man who will know what to do with them.
The jewels end up at a Meadowbank, a prestigious girls school, along with several people on their trail, and this is the kind of setting I like. It's a closed group of people, the students and the staff. Soon, the phys ed teacher is killed. The killer has to be at the school, but the investigation doesn't progress well, and two more people end up dead. Eventually (over 2/3 into the book), Poirot takes on the case.
Poirot doesn't do much investigating here. A bit of talking...