This is a Vincent Price vehicle that is loosely based on a Guy De Maupassant short story. The setup is eerie, speaking of how dark spiritual beings exist in our world, unseen by human eyes. "The Horla" is one such unseen supernatural being, one which has power over the minds of men and the natural world. Unfortunately, the film's pacing becomes quite grating by the end (was it really only 97 minutes?) and ends with some fairly predictable '50s/'60s cheesy horror.
In this tale, Price plays Simon Cordier, a magistrate in a French court in the late 19th century. When the magistrate has one final conversation with a prisoner convicted of multiple murders, the man tells Cordier that he did not commit the murders, but was compelled to by some unspeakable evil entity (the Horla) which took control of his mind and body. Then, for some reason or another, the Horla begins to stalk Cordier (it's rather clumsily presented, but it works). Fearing for his sanity, Cordier takes a vacation from his work and takes up his old hobby of sculpting, which leads him to encounter the model and enchanting muse, Odette (Nancy Kovak). And it is here that the Horla begins to work his magic on Simon Cordier. The Horla plays the devil's advocate, blackmailing Cordier into following his weakest urges.
A lot of Vincent Price films operated within a spectrum of horror-comedy, which is not to say that they were exactly funny, but had such an offbeat attitude it made them simultaneously amusing and creepy. Some of those vibes can be found here, and a number of Price's lines and expressions are totally charming (such as when he's smooth-talking Odette for the first time). And the way some of the "philosophical" ideas were presented -- they were so blunt it was comedic. I don't know if that much was intentional, but it did give the movie some color.
But at the same time the plot, characters and story are all too simple for how long the film runs. And the villain or mysterious antagonist, the "Horla", becomes pretty lame by the end. He gets reduced to the sort of unimaginative pseudo-science-fiction horror that filled out B-movies in the '50s and '60s. The typical spiritual/philosophical elements which litter "mystical horror" stories are here either cliché (the crucifix is able to ward off evil... again!) or just boring (the conversations with the Police Chief about whether or not criminals are born evil). And my other main criticism is that the film would be pretty terrible without Vincent Price in the lead role. Only Price carries the film by the end.
"Diary of a Madman" was a decent distraction for a lazy afternoon, but not a film that I'd watch again. Vincent Price has done some really excellent stuff, but this isn't one of his necessary works.
