The Hollow Man, published in the US as The Three Coffins, is a classic, if not the classic, locked room murder mystery from the Golden Age of detective fiction. It secured this accolade not only for its own apparently impossible pair of murders but also because of the bravura lecture given by crime-buster Dr Gideon Fell in which he outlines multiple different ways in which apparently impossible locked room murder mysteries can be done (and gives spoilers for several other pieces of detective fiction to boot along the way).
Of course, the book suffers the usual frailties of Golden Age detective fiction too: implausibly complicated plots and a profusion of characters of variable credibility, carrying out carefully choreographed activities to set up the plot and its camouflaging misdirections.
But that’s a bit like pointing out a stage magician isn’t looking and sounding like a normal human being. The point is to enjoy the trick – the misdirection and cleverness which makes the apparently impossible happen in front of your eyes, whether on stage with a rabbit and a hat or in a book with a collection of dead bodies.
In the Hollow Man, alongside a somewhat confusingly large cast of characters, rather thin dialogue and all the usual illogical insistences from a detective who won’t tell anyone else what he’s just worked out, you get two such glorious tricks. There is the man murdered in a locked room from which the murderer appears to have vanished into thin air. Then there is the man murdered up close out in the open, despite witnesses seeing no-one close by and the surrounding snow lacking footprints for anyone else.
Read for the enjoyment of the trick and not for the characters or quality of the dialogue.
If you like this, you might also be interested in the Bryant & May series by Christopher Fowler, which often pays homage to the Golden Age of detective fiction.