I’ve been watching a bunch of Agatha Christie’s Hercule Poirot mysteries on YouTube. As the Wikipedia notes: "After solving a case Poirot has the habit of collecting all people involved into a single room and explaining them the reasoning that led him to the solution, and revealing that the murderer is one of them."
What’s up with that? Others have used that trope, but did Christie invent it?
What I really want to know is: Why? How does the trope function? While Poirot could simply point out the guilty party and then explain how he figured it out, he never does that. There’s always an element of indirection in his technique, casting suspicion on other suspects before finally nailing the culprit.
Of course, this gives Christie, or the film-maker, an opportunity to review the case and thereby refresh it in the reader’s/viewer’s mind. What’s the function of the review?
ADDENDUM: The answer to this question might will be somewhere at Michael Grost's site, A Guide to Classic Mystery and Detection, which I've just discovered courtesy of David Bordwell's current (11 June 2012) piece, I Love a Mystery: Extra-credit reading. Grost's site is mind-bogglingly extensive and Bordwell's article is wonderful. Did you know that "in 1940, 40 % of all titles published were mysteries, and in 1945, an average four radio shows devoted to mystery were broadcast every day, each drawing about ten million listeners"? I didn't.