Locked Room Mystery : The Murders in the Rue Morgue, Edgsr Allan Poe
Before Hercule Poroit, before Sherlock Holmes, even before Jessica Fletcher, there was C Auguste Dupin.
The Murders in the Rue Morgue is often said to be the first detective novel. And it certainly has many of the tropes and themes which are now so familiar to fans of the genre.
And that's as much as I'm going to say because Booklikes is playing silly buggers and I'm fed up with it. But I have got a bingo which is good.