John Dickson Carr’s `The Hollow Man’ is a locked-room murder mystery with a difference (cue the music from track 3 of ‘The Soundtrack of the Trailer of the Film of Monty Python and the Holy Grail’). The book, aside from being a good example of the form, has the protagonists knowingly discuss locked-room murder mysteries; they either know that they are in a piece of fiction or that the case they are investigating is fiction-al (either interpretation works) and so Dr. Fell et al go out of their way to fill the reader in on what exactly is going on, whose testimony we can trust and, possible most importantly, just how many variations of the locked-room murder mystery there are.One observation that is made several times in `The Hollow Man’ is that of the probability of seemingly magical events. It is the showman O’Rourke who first touches upon it. He is asked, after the second murder (where a man is killed by a seemingly invisible gunman at close range in front of witnesses) how the murder could have occurred. O’Rourke is hesitant to postulate any technique by which it could be done for two reasons. The first is that most illusions are so simple in their execution that when presented with the solution people think that that can’t have been the case because they should have worked it out immediately. The second reason is that if the illusion relied upon a confederate then people consider that cheating and dismiss it. Later in the book Dr. Fell makes basically the same points in relation to the locked-room murder mystery plots and adds to this the problem of probability in fiction.If an improbable event occurs in reality then we bite the bullet, provided we are given a good explanation of it, and admit that events such as that can occur. If the same event occurs in a work of fiction then, even given a good explanation as to why it must have happened that way, the reader often feels cheated. Fell argues that this feeling of cheating is most associated with the locked-room murder mystery in that in this sub-genre of mystery fiction the seemingly impossible almost always rests upon one or two improbable events. He argues that readers are being unfair here; they are not objecting to the improbability of the event per se but rather the improbability of some of the preceding events and that when this is taken into consideration that this makes the solution is too obvious.The argument goes something like this: We are subjected to two contrasting responses; we want to be fooled but if its simple or if its complex we are going to be disappointed. We raise our expectations to such a level that we can never be satisfied. Dr. Fell/John Dixson Carr argues that locked-room murder mysteries are interesting because the seemingly impossible occurred. The answer cannot be too obvious because then it wouldn’t be much of a mystery but the revelation of how it was done disappoints many readers because the solution is clear given one or two facts that, whilst improbable, make sense of a mysterious situation.I think that one of reasons why Conspiracy Theories (and Conspiracism) is so popular is that, like the solutions to locked-room murder mysteries, the mundane (in a relative sense) explanation of what really happened ruins the mystery or magic of the Conspiracy Theory explanation. Mundane explanations often posit what we might consider to be improbable events or circumstances. Take the assassination of JFK (the oldies are still goodies, as they say); the official explanation posits that a lone man was able to make a very difficult shot and kill the President of the United States of America. This explanation is mundane; rather than a mysterious cabal of government officials (whose desired ends are never particularly clear) a lone assassin is posited. An improbable event is used as a keystone of the explanation; the three shots Oswald fired from his vantage point. The magic and mystery of the Conspiracy Theory is replaced with an explanation that, frankly, is a little disappointing (in a narrative sense).Food for thought.