Sherlock Holmes sends Dr. Watson to Lausanne to investigate Lady Frances Carfax's disappearance since he himself is too busy in London. Lady Frances is a lone, unwed woman denied a rich inheritance on account of her sex. She does, however, carry valuable jewels with her. It is also her habit to write to her old governess, Miss Dobney, every other week, but for the past five weeks, there has not been a word from her.