Saki, who's real name was Hector Hugh Munro, was a British writer of witty and sometimes macabre stories. Critics consider him a master of the short story, and he is often compared to O. Henry and Dorothy Parker. Saki wrote hundreds of wonderful stories.
In this story, Mrs. Caball, the "grand dame" of a society family, mistakes Lady Carlotta for the governess she has come to meet at the train station. The Lady does nothing to correct her error. On being asked where her luggage is, she reponds that "Someone lost it." One of Lady Carlotta's very excellent rules was "the absent are always to blame". Lady Carlotta throws aside her own plans and becomes a very interesting governess, not at all what the family expected.