The Mystery of the Blue Train by Agatha Christie
Yes, Poirot again. I've been on a bit of a kick lately, I know. I'm almost reading/re-reading the series in order. I #4 earlier this year and obviously still remember it well. I skipped #5 because I don't like it. So now we're at #6, The Mystery of the Blue Train.
There's a lot of lead up before the murder. We meet an heiress whose millionaire father gives her a fabulous ruby to cheer her up a little. She and her husband are having problems and, as the father sees it, her only real option is to divorce him. We meet the husband and his mistress, a dancer who is only interested in rich men, which he won't be if his wife divorces him. We meet a not necessarily above-board jewelry merchant and his daughter. Finally, I think, we meet a lovely young woman, Katherine Grey, who has recently become rich herself, after the elderly woman she was a companion to...