Dead Man's Folly (1956)

Not a classic but a very solid Poirot mystery. I picked it up a) because I hadn't read it before and b) because it featured Ariadne Oliver, probably my favorite recurring Christie character, the dry and self-deprecating mystery novelist. Poirot attends a fete in which there is a scheduled murder hunt, a kind of figure-it-out-yourself mystery devised by Mrs. Oliver. Naturally the young girl who is hired to play the murder victim winds up strangled for real. The solution is both ingenious and a little bit out of left field.

Mrs. McGinty's Dead (2008)

A perfect televised adaptation of Agatha Christie's novel, beautifully filmed and very faithful to the novel. The one change they make, that there are two women who are profiled in the newspaper article instead of four, is a good change. I particularly loved Sarah Smart as Maude Williams, and, of course, Zoe Wanamaker as one of my favorite Christie characters, Ariadne Oliver.