Vincent Price stars as a French magistrate who becomes possessed by a murderous spirit that jumps from person to person, forcing them to carry out its bidding. When Price’s character begins to fall in love with a married posing model (Nancy Kovack), the spirit commands him to kill the woman’s husband. Price’s attempts to outwit the spirit become his undoing in a tragic third act.
British horror films from the 50s, 60s and 70s have a very deliberate pacing that see their characters spending long scenes together coming to realizations and fully comprehending the supernatural events that occur around them. The pacing, frankly, is an acquired taste. But Diary of a Madman‘s languid pacing tests even the most devout fan’s patience. The long middle act of the film has very little mention of the evil spirit, focusing almost entirely on Price’s budding affair with Kovack’s character. While Kovack is indeed lovely and charming, it almost feels like a different movie entirely until the evil spirit finally returns again.
Diary of a Madman drags in many places and fails to weave its two story lines into one, cogent narrative. But the film starts off well and mysterious, as we begin to learn about the evil spirit. And the final five or ten minutes actually border on exciting as Price enlists a priest to help him save a woman he’s stalking — as the spirit takes the reigns of a horse-drawn carriage to mow them both over.