American professor John Holden arrives in London for a conference on parapsychology only to discover that the colleague he was supposed to meet was killed in a freak accident the day before. It turns out that the deceased had been investigating a cult lead by Dr. Julian Karswell. Though a skeptic, Holden is suspicious of the devil-worshiping Karswell. Following a trail of mysterious manuscripts, Holden enters a world that makes him question his faith in science.

Dana Andrews
as Dr. John Holden

Peggy Cummins
as Joanna Harrington

Niall MacGinnis
as Dr. Julian Karswell

Maurice Denham
as Professor Henry Harrington

Athene Seyler
as Mrs. Karswell

Liam Redmond
as Professor Mark O'Brien

Reginald Beckwith
as Mr. Meek

Ewan Roberts
as Lloyd Williamson

Peter Elliott
as Professor K.T. Kumar

Rosamund Greenwood
as Mrs. Meek
John Chard
You know, the devil has something here. Very pleasant. Dr. John Holden arrives in England to attend a paranormal convention where the recently deceased Professor Harrington had intended to expose Dr. Julian Karswell as being the leader of satanic cult. Upon learning of Harrington's death, Holden ...