The Sleeping Cardinal, also known as Sherlock Holmes' Fatal Hour in the United States, is a 1931 British mystery film directed by Leslie S. Hiscott and starring Arthur Wontner and Ian Fleming.

The film was produced at Twickenham Studios in London with sets designed by art director James A. Carter.

Adair's concerned sister calls for the assistance of Sherlock Holmes and Dr. Watson to investigate the reasons for her brother's gambling excesses and depressed moods.

In a contemporary review, The New York Times wrote: "There are secret doors leading into strange compartments and rooms, and there are scufflings and caterwaulings in dark corridors.

Detective Holmes barely escapes with his life, and the dear Dr. Watson is drawn away by innumerable red herrings.