The Private Life of Sherlock Homes

Arthur Conan Doyle (characters) (as Sir Arthur Conan Doyle), Billy Wilder 1970

IMDB: http://www.imdb.com/title/tt0066249/

When a bored Holmes eagerly takes the case of Gabrielle Valladon after an attempt on her life, the search for her missing husband leads to Loch Ness and the legendary monster.