4:50 from Paddington by Agatha Christie

I loved this murder mystery. The conceit is really quite wonderful: a little old lady watches a murder being committed but can't do anything about it because she's on a different train at the time. Although this novel features Miss Marple, she does less solving than usual (Lucy Eylesbarrow taking on much of the legwork) and is actually on the scene, so it feels a little more like a Hercule Poirot mystery than usual. Of course, there's a wonderful, decaying family home, and the usual limited number of suspects scenario. I really enjoyed this mystery.