Night of the Demon - 1957

American scientist John Holden arrives in London for a conference on parapsychology to discover that the priests that has been killed in a freak accident the day before. As it happens that the deceased had been investigating a cult lead by Dr. Julian Karswell. Though a skeptic, Holden is suspicious of this Karswell. Following a trail of manuscripts that are mysterious, Holden enters a world which makes him question his own faith.