Depending on the country where you saw this movie, if you have seen it, the title may have been Curse of the Demon.

Dana Andrews plays Dr. John Holden and American psychiatrist and expert in cults who is traveling to England in order to help a friend de-bunk a local witches cult led by Julian Karswell, plays with malevolent charm by Niall MacGinnis. When Holden arrives he discovers that his friend has died in an auto accident that few see as mysterious save for his friends niece, Joanna played by Peggy Cummins. Who is certain that Karswell and the cult are responsible. Holden, a good and devote skeptic, refuses to believe in hocus-pocus and approaches the issue as a rationalist. Karswell, insistent that he and his followers be left alone claims to have placed a death curse on Holden and the battle of wills between the two men starts.

While I do not yet have a copy of Night of The Demon in my library I do hope to add it soon. I recently re-watched it on the horror streaming service Shudder and the film still plays quite well. The movie was directed by Jacques Tourneur who also directed the classic genre feature Cat People. Turneur wanted to make this film also an ambiguous one where the exact nature of the threat could be seen as either psychological and demonic but he was overruled by the producers and the threat’s nature is fairly explicit from the opening reel.

This is not a great film, but it works and is well worth at least one viewing.