Inner Sanctum is a 1948 American film noir directed by Lew Landers based on the Simon & Schuster book series of the same name and the Inner Sanctum Mystery radio series. A previous film series of the show had been produced by Universal Pictures until 1945. It is the first and only film of M.R.S. productions, the initials of Richard B. Morros, Samuel Rheiner and Walter Shenson.

Plot
The film follows a murderer who is on the run and hiding out in a small town. As the story progresses, a boy who is sharing his room with the stranger realizes he has witnessed the man killing a woman.

The story begins on a train at night where an elegantly dressed woman (Gail Patrick) meets a mysterious foreigner (Fritz Leiber, Sr.). She is fascinated when he is able to predict every shake and bump of the train, and every flickering moment of darkness, an instant before they occur, though he claims he has never ridden on this train before. He is, evidently, gifted with some sort of second sight. He offers to tell her a story about events that began at some unspecified time at the next station. The point of view then shifts to acting out this narrative, which starts with Harold Dunlap (Charles Russell) inadvertently killing a woman with whom he has had a violent fight on the platform. He places her body on the open rear end of a departing train and then goes in search of a boarding house where he can hide out for a time. There he encounters a young woman named Jean Maxwell (Mary Beth Hughes) with whom he appears to fall in love and the young boy who recognizes him.

After the film returns to the present it is revealed that Dr Valonius has an immediate and compelling interest in telling the story and the moral it teaches. We are left to speculate that he may in the future choose other passengers to whom he will tell weird stories which have been revealed to him via his psychic powers, somewhat in the manner of the eponymous narrator in the radio series The Mysterious Traveler.

Cast
Charles Russell as Harold Dunlap
Mary Beth Hughes as Jean Maxwell
Dale Belding as Mike Bennett
Billy House as McFee
Fritz Leiber, Sr. as Doctor Valonius, the Seer
Nana Bryant as Thelma Mitchell
Lee Patrick as Ruth Bennett
Roscoe Ates as Willy
Eddie Parks as Barney
Eve Miller as Marie Kembar, Dunlap’s Fiancée