Night of the Demon 1957 (a.k.a. Curse of the Demon

Night of the Demon (in the United States, released as Curse of the Demon) is a 1957 British horror film, produced by Hal E. Chester and Frank Bevis.
Directed by Jacques Tourneur and starring Dana Andrews, Peggy Cummins and Niall MacGinnis. It is adapted from the M. R. James story "Casting the Runes".
The film's storyline concerns an American psychologist who travels to England to investigate a satanic cult suspected in more than one death.

Turbulent artistic differences arose between producer Hal E. Chester on one side and director Tourneur and writer Charles Bennett on the other over Chester's plan to show the demon on screen, but Chester prevailed. To accelerate the pace and make the film more commercial, the 96-minute original feature was trimmed down to 82 minutes prior to its release in the United States.[2] This shortened version was retitled Curse of the Demon, playing in June 1958 as the second half of a double feature with either The True Story of Lynn Stuart or The Revenge of Frankenstein (1958), depending on the local film market.
In England, Professor Harrington begs his rival, Dr. Julian Karswell, to rescind a curse he inflicted on him; in return, Harrington will cease his investigation into Karswell's Satanic cult. After learning that a parchment he gave Harrington has been destroyed, Karswell promises to do what he can. As Harrington arrives home, he sees a gigantic demon in the trees. Harrington tries to escape in his car but crashes into power lines. The authorities declare electrocution as the cause of death.

Dr. John Holden arrives in Britain to attend a convention at which Harrington had intended to expose Karswell's cult. He is informed that the only link between Harrington's death and Karswell's cult is a man suspected of murder, Rand Hobart, who has fallen into a catatonic stupor. While Harrington's collaborators consider the possibility of supernatural forces, Holden rejects such an option.