My obsession with all things occult and satanic led me to re-watch this 1957 British horror. I recalled that it was a weaker cousin to such classics as The Devil Rides Out and Blood on Satan's Claw and I was right. The story generally nips along but gets bogged down in places. Its troubled production history no doubt contributes to the occasional meanderings.
The plot is based on the classic short story by master-of-shivers MR James. As befits its short form, James' tale is far less complex than the film and focuses on a small number of male protagonists. The story of a nefarious cult-leader issuing occult equivalents of Treasure Island's black spots was padded out by the studio, most notably with a romantic sub plot. A sticking point in the production was the debate about whether to make it explicit that the killings are the work of a summoned demon, or more open to interpretation. The former was eventually chosen, probably to put the movie more firmly in the 'horror' bracket than as a harder-to-market occult thriller. I have no problem with the decision, only the way the demon is rendered. The smoky start to his manifestation is good, but when the actual beastie appears his animation is rather lacking.
The film is a good romp for a Sunday afternoon, but doesn't quite live up to its potential. Writers like my beloved Nigel Kneale do a much better job of building the suspense, usually by relating old legends and using evocative locations. There are nods to both techniques in Night of the Demon but they're brief and the adaption relies too much on melodrama.